OOSHIMA YUMIKO

Chibi-Neko is a young kitten who has been abandoned. She doesn’t know she has been abandoned, and doesn’t know the difference between cats and humans. Indeed, she imagines herself as a human girl and believes she will become human someday. She is found and rescued by a boy named Tokio, who has just graduated from high school. However, he flunked the entrance exams and now is not sure of his future or what he will do. Chibi-Neko soon begins to love Tokio and wants to become a human and marry him someday. But then she sees Tokio with another girl in the park, and sees that he is in love with this girl. She also keeps getting visited by Raphael, a mysterious male cat who tries to tell her that cats cannot become human, they are always cats. What will Chibi-Neko do?Was adapted into 1984 anime movie.

(from wikipedia.ja):Simon was taken in by his uncle, Gilles, an ecologist, after his parents died, but he ended up fighting with his rival Jean-Claude over his cousin Joca, his uncle's daughter. Joca, worried about Simon's weak fighting spirit, gives him a medicine developed by his father that makes him stronger, but it turns out to be a s**-transforming drug. Simon is placed in the care of his uncle's friend in England, and when his uncle shows Simon his own chromosomes, Simon is forced to accept. A month later, Simon was pronounced dead in England.Seven years later, after the death of his mother-in-law, Simon, now named Solange, was taken in again by his uncle and sent to live with Joca. Jean-Claude, who is engaged to Joca, becomes disturbed by Solange as a woman.