Shinji, a high school freshman, gets dumped by his girlfriend on Christmas Eve because she finds him 'creepy'. Devastated, he's approached by Rika, a classmate who's also a gal. Rika comforts him and unexpectedly asks him to be her boyfriend, revealing her plan to use him to get revenge on her ex-boyfriend. They start a fake relationship to make Shinji's ex-girlfriend jealous. Initially a revenge plot, their relationship deepens, and Rika transforms from a gal into a beautiful, refined woman. Meanwhile, Shinji's ex-girlfriend realizes her mistake, but it's too late; Shinji and Rika are truly in love.