Kakumei no Hi

Kei is a normal--if very pretty--young boy in high school. One day, he falls ill and is taken to the hospital. They find, much to everyone's surprise, that "he" actually has a female genotype even though "his" phenotype is male!! A little bit of surgical work solves the problem, and cool male hero Kei becomes innocent female heroine Kei. And what a female! "He" was cute before, but she is a beauty now.

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Kei Yoshikawa, a normal - if very pretty - boy in high school is one day informed that he is genetically female. The shocking relevation causes Kei to restart his life as a beautiful girl named Megumi, while keeping it all a secret from her very handsome male friends. And of course they immediately find out, but all begin hitting on her?!