Banana Bread no Pudding

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Two manga from the 70s who share the same aesthetic. The discussed themes are similar : they're both about society outcasts and the problems lgbt people have to undergo. They also address topics such as sexuality or philosophy. Also, they both have an atmosphere and a particular drawing style that makes you wonder what's real or not. 

Banana Bread Pudding is from the same period and drawn in a style with a similar aesthetic. These are both slice of life stories about about people who have trouble dealing with their own feelings of love.  

If you enjoyed "Revolutionary Girl Utena", you can give a try to "Banana Bread Pudding", too. Though I would say that BBP have a connection to Utena anime rather than manga. Both stories tell about girls' adolescense in strange but touching manner, using postmodernistic techniques. (Besides, there is a funny coincidence: Saeko looks exactly like Anthy, and her brother's appearance reminds me of Akio.) 

Although Thomas no Shinzou is a lot more dramatic and angsty, both series deal with characters grappling with self-discovery and facing their true selves, and how this influences the way they interact with others. Both also have themes of repressed or closeted sexuality, and since they're both '70s shoujo series they have a remarkably similar overall aesthetic and presentation.