Takumi Musashino was formerly an ordinary high school boy, but his life changed when his body transformed into that of an alluring high school girl due to an experimental gene therapy treatment he underwent after being diagnosed with a terminal illness. She astonishes her classmates with her new form, eliciting mixed reactions from them. While girls like Anri Sogahara provide her with crucial advice on adjusting, her male peers start to view her as an object of their desires... Although Takumi feels both confused and nervous about her new existence and appearance, she will soon discover the wonderful pleasures of being a young, adolescent woman.