Why the Hell Are You Here, Teacher!?

Why the Hell Are You Here, Teacher? (Nande Koko ni Sensei ga!?) is an ongoing Ecchi Romantic Sex Comedy manga by Soborou, which began serialization in Weekly Young Magazine in 2017. An animated adaptation has been released in Spring 2019.

Kana Kojima, a high school Japanese language teacher at Kawanuma West, is famous for being a "demon teacher." However, in front of high school student Ichirou, she seems to be air-headed and clumsy, and he keeps finding himself in perverted situations with her in places like the men's bathroom, the men's bathhouse, the pool, the school infirmary, and elsewhere.

And they're not the only ones, with several students finding themselves in perverted situations with their teachers.

General Tropes

• Accidental Kiss: It doesn't happen as often as "accidental groping" but it does happen to more than one couple.
• Accidental Pervert: Every male protagonist finds himself in a compromising position with his respective teacher, almost always exposing or touching something.
• Adaptational Early Appearance: The anime has Rin and Mayu, the second couple from the manga, show up in the first episode. Mayu even replaces the unnamed generic teacher from the second chapter of the manga.
• Adaptational Expansion: The bonus 13th episode of the anime is based on the omake chapter of the 4th volume, but instead of focusing solely on Tachibana and Tanaka, it also shows what the previous three couples were doing during that time.
• Alliterative Name: Nearly every character. Kana Kojima, Mayu Matsukaze, Hikari Hazakura, Saki Satou, Takashi Takahashi, Wataru Watanabe, and Izumi Inokawa. The seventh volume even introduces Repetitive Name Yamato Yamamoto and Ouka Okamoto.
• Aloof Dark-Haired Girl: Izumi Inokawa, the teacher of the sixth volume, has long dark hair, wears dark clothes and has a quiet and rather creepy demeanor.
• Art Shift: Anyone can look normal one second and have an exaggerated and cartoonishly wacky facial expressions in the next, and the series has a wide variety of them, most of which involve Blank White Eyes.
• Ascended Extra: Mayu's little sister Saya was introduced as a supporting character with infrequent appearances in volumes 2 and 3. Come volume 5, and she is now part of the central Love Triangle of the volume, effectively being promoted to main character status.
• Ass Shove:
  • Satou is forced to give Kana a suppository when she gets a cold. Making matters worse, since he was blindfolded to let Kana keep her dignity, the first try was... “not successful.”
  “No, not *that* hole... stupid... further up!”
  • The next day when Satou gets her cold, Kana returns the favor when she finds out he pretended to be sick to skip class. And she's not gentle about it.
• Child Prodigy: Homura is 16 years old, yet she already has a Bachelor's degree and had various research papers published. Volume 5 starts with her becoming a Language Teacher for students of her age.
• Comic-Book Time: Subverted, the Love Triangle story arc in Volume 5 takes place a short time after the other three which happen concurrently, Mayu is stated to have recently married Suzuki, so there wouldn't be any obvious signs of aging.
• The Comically Serious: Most of the comedy of volume 4 is derived from how Chizuru's seriousness doesn't fit the Ecchi nature of the manga.
• Contrived Coincidence: How the plots of many chapters start; the opening narrations of the main characters show they are just as incredulous as the audience. They usually begin with "This is X. I'm sure this is X. Then why is Teacher here!?" with the teacher of the volume somehow being in the same room as them, in spite of how unlikely that is.
• Cool Big Sis:
  • Mayu is Saya's older sister and is one of the nicest teachers, but is a bit less mature than Saya.
  • Izumi has a younger brother and really tries to cheer him up during an athletic meet.
• Couch Gag: In the anime, the start and end of the opening credits and the full ending credits change to showcase the "main" teacher of the current arc which includes a "Do It Yourself" Theme Tune ending done by said main teacher.
• Curtains Match the Window: Quite a few characters have eyes that match their hair color. Mayu, Chizuru and Ouka are some examples.
• Dark Is Not Evil: Inokawa has long black hair, wears dark clothes and has a creepy demeanor about her, which freaks her students out. But deep down she's really just a sweetheart who's trying to do her best as a teacher and getting to know her students.
• Defrosting Ice Queen:
  • Downplayed with Kana. Although she does mellow out over time, she still retains her demon persona.
  • Chizuru is famous for her emotionless demeanor, but after interacting with Kou, her personality becomes slightly more expressive.
• The Dreaded:
  • Kana is known as "Kojima the Demon Teacher" for her strict teaching that even delinquents are scared of her.
  • To a lighter degree, Inokawa is known as the "Stalker Ghost" for doing extensive research on her students and revealing that she knows much more about them than they feel comfortable with.
• Easily Forgiven: Most of the awkward situations end with the guys apologizing profusely and the teachers dismissing it as an accident, although there are exceptions.
• Emotionless Girl: Chizuru is believed to be this by all of her students (thus her nickname "Absolute Zero"). In reality, she has emotions like any other person, but they don't show in her face most of the time.
• Eye Poke: Ichiro tries pulling this on Rin when they both see Kana in a swimsuit at the local pool, except Rin is wearing a pair of glasses. When they see Mayu wearing a swimsuit, it's Kana who does this to Ichiro.
• Face of a Thug:
  • Not only is Rin very tall for his age, but his face seems to instinctively switch to a glare whenever he is unsure of how to approach people. At the start of Volume 2, Satou is his Only Friend because he is the only one who knows he is a Nice Guy inside.
  • Kana herself can fall into this whenever she has an intimidating glare, which is enough to make babies cry.
• Forgotten First Meeting: Satou met Kana when she was a teenager, and he was a kid. Satou forgot their meeting, but Kana never did (although she didn't realize that the kid she met was Satou), prompting for him wondering if he's the reason why she is known as "Kojima the Demon Teacher."
• From Bad to Worse: Just about every chapter is structured this way. Once a teacher falls into some kind of embarrassing situation with a student, the student's efforts to get them out of it or make things right only makes it worse. They'll accidentally grab their clothes or underwear and take them off, have the teacher fall on top of them just to be grabbed in the worst possible spot, or risk exposing them in front of others. It all works out in the end, though. Somehow.
• Funbag Airbag: Inverted in chapter 101 when Kobayashi faceplants in Minamoto's boobs as she leaps in front of him to stop him opening the box with her manga supplies.
• Fun T-Shirt: In chapter 58, Watanabe is wearing a T-shirt that says "UST".
• Gender Bender: One of Nana's many inventions is a drink and pill that changes a person's genitals into the opposite sex for a brief time. Tadashi is given the pill variant when he tries to convince Kurumi that he's not the man she fears he is and fails because of how quickly it wears off, and Kurumi is later treated to the pill variant when she visits his school, needs to use the restroom, and nearly gets caught herself.
• Gentle Giant: Rin is huge for his age, but he is just as nice as any of the other guys.
• Has a Type: Kojima's criteria for men involves a younger man who can take care of people, and can get along with kids. Satou (un)fortunately fits all three of these criteria.
• Hot Teacher: This is the whole point of the story since all the female teachers have killer bodies.
• Hotter and Sexier:
  • Normally each couple gets ten chapters for themselves. But sometimes the author publishes "extra chapters" outside of that count. Those chapters are pretty much guaranteed to be even more explicit than the usual chapters.
  • The main story also becomes much more daring in how far it can take the Fanservice starting with the Love Triangle arc in volumes 8-10. Some chapters in those volumes are bordeline softcore porn.
• Huge Guy, Tiny Girl: Rin and Mayu share this dynamic, as he's the tallest of the male protagonists, while Mayu is among the shortest teachers.
• I Am Not Pretty: Neither Chizuru nor Izumi consider themselves very sexy. Kou and Wataru would easily tell you otherwise.
• In-Series Nickname: At least 6 of the teachers have earned one: "Kojima the Demon" for Kana; "Matsukaze the Saint" for Mayu; "Absolute Zero Tachibana" for Chizuru; "Inokawa the Stalker Ghost" for Izumi; "Prince Kurisu" for Kurumi; and "Lone Wolf Minamoto" for Minamoto.
• Intimate Lotion Application: When Ichiro finds his Hot Teacher Kana on the beach, he has a hard time interacting with her already due to seeing her in a bikini, and he only gets even more nervous when she requests him to rub sunscreen on her bare back. He does so apprehensively, wondering if she's being affectionate and flirty with him on purpose. Unfortunately for him, he says his thoughts out loud, which startles her and makes her turn around, causing him to both accidentally grope her breasts and get an eyeful of her topless. She promptly has a Naked Freak-Out and covers herself with her hands before dashing away mortified.
• Jailbait Wait: Slight variation: some of the teachers make a point to not enter a serious relationship with their students until they have graduated from school.
• Jump Scare: Happens in the seventh volume when Ouka gazes upon Yamato practicing to win her over, and Izumi pops out from behind her, scaring the daylights out of the pop idol teacher.
• Laundromat Liaisons: In Chapter 5, Satou and Kojima run into each other at a laundromat in the middle of a storm. He offers his shirt while hers is drying, but it ends up becoming a Sexy Soaked Shirt as well when a bottle of detergent falls on them.
• Let's Wait a While: After getting together, the Omake chapters show that Kana and Izumi aren't ready to go all the way with their new boyfriends. Not that it doesn't stop the former from fantasizing about it.
• Like Brother and Sister: Before becoming romantically involved, this was Hikari and Takashi's relationship, Takashi even calling Hikari "Hika-nee" in private, being Childhood Friends due to both of them being in families where both parents worked. Their first episode is all about how both have changed.
• Literally Loving Thy Neighbor: In their introduction chapter, Kobayashi finds out Minamoto-sensei is moving into the apartment next door from him.
• Living a Double Life: Ouka Okamoto isn't just a new teacher in the seventh volume, but her alter ego is an airheaded Idol Singer named Sakura Okamoto, and she doesn't want her students or fans to connect the dots.
• Love Triangle:
  • The fifth volume differs from the previous four by having three main characters: The obligatory male main character Yorito, Child Prodigy Homura, and Mayu’s younger sister Saya. The Teacher/Student Romance theme is preserved despite them all being around the same age because Homura has just become a teacher and Saya used to tutor Yorito in daycare.
  • While each volume revolves around one couple, Volume 8 marks a huge change for the series by dedicating three volumes around Bishōnen Tadashi Nakamura and the two teachers that fall for him: Tomboy Kurumi Kurisu and Mad Scientist Nana Nanjou. Volume 8 shows how the two teachers begin to fall for him, and when Tadashi is asked which one he likes at the end, the story splits into two paths: Volume 9 is the "Nanjou Path" and Volume 10 is the "Kurisu Path". While Tadashi appears in all three volumes, Kurumi only appears briefly at the beginning of Nanjou's path, and vice versa for hers.
• Miss Conception:
  • Kana admits that she's not an expert on sex and it shows. In one of the early omake chapters, she accidentally trips and goes down on Satou, and tells him they should start thinking of names for the baby. Considering there was no actual intercourse involved, he's baffled.
  • To lesser degree, Izumi goes down on Wataru in her omake chapter because she believes that couples do it to relieve their stress and nervousness, not because of any physical stimulation involved.
• Nice Girl: Mayu is known in her school as the kindest and most tolerant teacher.
• Nice Guy: All the male main characters are this to some extent. It plays a major role in them getting the interest of a Hot Teacher.
• No Social Skills:
  • Chizuru has no idea of how she is supposed to interact with her students.
  • Izumi has a tendency to pop up out of nowhere and bring up the darkest secrets of her students.
• Odd Friendship:
  • Kojima is seen as the scariest teacher in the school and has zero popularity with the students, while Mayu is seen as the kindest and is the most popular. The two are good friends.
  • Similarly, Chizuru goes to Hikari when she needs advice on how to get closer to her students, despite their personalities being polar opposites.
• Oh, Crap!: All over the damn place. There are too many incidents to count where the teachers and students end up causing each other trouble, and their attempts to remedy the situation only makes it worse. It's mostly from the students when they accidentally grope their teachers or cause them to lose their clothes, but the teachers are prone to this as well as a result of their clumsiness.
• Older Than She Looks: Mayu looks like she could be Rin's classmate, or maybe even his younger sister, but not his teacher.
• One Degree of Separation: The Rotating Protagonists are all connected through a net of relationships that gets more and more implausible as the series goes. The first set of protagonists Satou and Kojima are friends with the second set of protagonists, Rin and Mayu, respectively. Those two then go to another school to work in a combo event, and the teacher-student pair they meet there – Hikari and Takashi – also get romantically involved with each other. Then the series introduces Kou, the former student council president of Takashi's school who went to the same junior high school as Satou and Rin, and who also gets in a relationship with his teacher Chizuru, who happens to be friends with Hikari. And after all that, a Child Prodigy becomes a teacher in the first school, is introduced to the students by Kojima, and gets involved in a Love Triangle between herself, Mayu's younger sister Saya, and another student called Yorito, with all three of them being Childhood Friends. It continues on from there, with each new couple being connected to a character from the previous volumes in some way or another.
• Only Friend: Satou is this to Rin at the start of volume 2. He tries to distance himself from Rin a little in part because he wants some alone time with Kojima, and in part because Satou wants Rin to make more friends so Rin won't become reliant on him.
• Out-of-Genre Experience: The manga is generally a Like Reality, Unless Noted Sex Comedy, but shifts to more of a Science Fiction story for the chapters focusing on Nanjou-sensei, who is a Mad Scientist able to invent a way to enter other people's dreams and pills that can temporarily and instantly change someone's sex. It shifts back to normal in volume 10, when the focus moves back to Kurisu-sensei.
• Potty Emergency: Some of the situations involve one of the teachers being stuck in a bad position, and it goes From Bad to Worse when they have to use the restroom and are nowhere near one. Or if they are, it's usually the men's restroom and they risk getting caught.
• Potty Failure:
  • The very first story ends this way. When Satou finds himself trapped in the boys' restroom with Kojima (who was using it since the woman's restroom was being cleaned), after everything that happens, the poor guy can't hold it in and we're reminded of the reason he came into the restroom in the first place.
  • In Chapter 29, Hikari Hazakura gets stuck on a broken floorboard with her underwear in full view on the lower floor while her upper body is stuck on the upper floor. The cold temperature in the abandoned school she is in causes her to need to pee. Someone below manages to slide them to the side and get a bucket, but someone coming by causes her underwear to shift back into place, and she ends up peeing through her clothes.
  • Homura suffers from this in Chapter 42, which reminds Yamato that she was the same young foreign girl from many years before who peed herself, since she didn't know enough Japanese at the time to ask where the restroom was. Both times, he soaks her in water before anyone could learn what really happened, making it look like he had pulled a mean prank on her instead.
• Pun-Based Title: Nearly every chapter title from Chapter 30 on is a pun.
• Raging Stiffie: A frequent gag, and most of the guys try to hide it out of embarrassment.
• Rei Ayanami Expy: Chizuru. She has pale hair, is introduced as an Emotionless Girl, and her character arc is about learning how to interact with others as she gets closer to Kou.
• Romantic Comedy: The stories are filled with cute and romantic elements, and the ridiculousness of the ecchi situations and wild reactions from everyone makes it funnier than one would expect.
• Rotating Protagonist: Every volume of the series focuses on a different couple. The previous main characters never disappear, but they are reduced to a supporting role.
• Rule of Sexy: The series will often ignore the laws of physics and even common sense for the sake of getting attractive female teachers in erotic situations with their male students.
• Scary Flashlight Face: When Satou gets home from his class's haunted house, his mom is waiting for him like this.
• Seductive Mummy: In Chapter 9, Kana dresses as a very shapely mummy for the School Festival's Haunted House.
• Sensei-chan: All the teachers aren't that old when compared to their students, and most of them have dorky traits.
• Sex Comedy: Many of the embarrassing situations the teachers and students have together are Played for Laughs because of how unexpected things happen, and their efforts to get themselves out of it only makes it worse.
• Sexy Discretion Shot: Occurs in the omake chapter between Chizuru and Tanaka after they get together. It turns out she accidentally took him to a love hotel, and after things go wrong in the bathroom, she suggests they try again and get it right. The next morning reveals they had sex, but it wasn't as pleasant as Chizuru hoped.
• Sexy Santa Dress: Chizuru spends Christmas with Kou wearing one of these. She really likes Christmas.
• Shipper on Deck: Satou's mother ships her son with her old friend Kana.
• Stern Teacher: Kana "The Demon" Kojima. Rumors say she is stern even with the parents of her students.
• The Stoic: What Chizuru is, rather than the Emotionless Girl her students believe her to be. She has had trouble expressing her emotions since she was small.
• Suck Out the Poison:
  • Ichiro attempts this on Kana when she gets bitten while swimming at the beach, in the worst possible spot. She passes out, but not because she was poisoned, but because he hit the wrong spot.
  • This gets a Call-Back in Chapter 100, where Kurisu thinks Tadashi was bitten by a snake on his penis, and ends up giving him a blowjob before he can explain.
• Sugar-and-Ice Personality:
  • Kana is feared by nearly everyone around her, but her encounters with Satou reveal she's shy and clumsy.
  • Chizuru is most of the time calm and aloof, but her sweet side comes into view when interacting with Kou.
• Suggestive Collision: It's impossible for the characters to bump into each other and not get themselves entangled in each other's assets.
• Tan Lines: As expected of a swimming teacher, Hikari has several tan lines.
• Teacher/Student Romance: The underlying premise for each arc, with the respective pairing becoming closer as their story progresses.
• Thanks for the Mammary: All the time. One example is when Satou is putting sunscreen on Kana's back in Chapter 10, and she turns around after accidentally saying "I really like you", only for him to end up with a handful of breast.
• Title Drop: Many chapters start with the male main character asking the same question from the title, or some variation of it.
• Tsundere:
  • Kana starts as mostly harsh, but after enough incidents with Satou, she becomes mostly sweet.
  • Homura is stated to be one, but her difficulty with being upfront with her feelings unintentionally keeps her on the "tsun tsun" side.
  • Ouka acts coldly toward Yamato, but it's only a front because she can't be upfront about her real feelings for him due to being a teacher and an idol.
• Younger Than They Look: Rin. When he and Mayu first met, she believed that he was older than her, and was shocked when she learned that he was still a student.