Chiaki Yasumi has it all: looks, grades, athletic talent, wealth, and a beautiful sister. Yet he faces one persistent frustration despite his privileged life he has never been popular with girls and has never experienced love. Determined to change his fortunes in high school, he vows to reinvent himself. But on the morning after making this promise, Chiaki wakes up to find he has transformed into a girl. Shocked at losing his proud male appearance, he is nonetheless surprised to see a very cute girl staring back from the mirror. He rushes to show his twin sister Kaede, who is highly popular among girls, only to discover that something equally strange is happening to her.

The story follows Chiaki navigating high school life in a new body, dealing with the romantic complications of his situation while his family consists of more than just his twin. His older sister Yuko is a mad scientist, hinting at a possible scientific explanation for the transformations. Mei Nishiarai, Chiakis childhood friend and a popular classmate, also plays a key role in the unfolding events. The narrative blends romantic comedy with body-swap and sibling dynamics, as Chiaki finds his first love in circumstances far too embarrassing to ever confess to anyone. As the story progresses, the relationships among the three beautiful Yasumi sisters and those around them develop, exploring themes of identity, love, and the absurdity of a long-desired fresh start taking an unexpected form. The manga is serialized in Hakusenshas Young Animal magazine.