In Fujisawa, Sakuta Azusagawa is in his second year of high school. Blissful days with his girlfriend and upperclassman, Mai Sakurajima, are interrupted by the appearance of his first crush, Shoko Makinohara.

Puberty Syndrome—a rumored, mysterious syndrome that only affects those in their puberty. For example, a bunny girl suddenly appeared in front of Sakuta Azusagawa. The bunny girl's real identity is Mai Sakurajima, a teenage celebrity who is currently an inactive high school senior. For some reason, her charming figure does not reflect in the eyes of others. In the course of revealing the mystery behind this phenomenon, Sakuta begins to explore his feelings towards Mai. Set in a city where the skies and seas shine, Sakuta unfolds the meaning behind his bizarre encounters on women with the said syndrome.

Spring time in April and the last of the cherry blossoms are still in bloom. The usually aloof bookworm with no interest in others comes across a book in a hospital waiting room. Handwritten on the cover are the words: "Living with Dying." He soon discovers that it is a diary kept by his very popular and genuinely cheerful classmate, Sakura Yamauchi, who reveals to him that she is secretly suffering from a pancreatic illness and only has a limited time left. It is at this moment that she gains just one more person to share her secret. Trying to maintain a normal life as much as possible, Sakura is determined to live her life to the fullest until the very last day. As her free spirit and unpredictable actions throw him for a loop, his heart begins to gradually change.

A college student spends his year at the seaside town of Izu, having fun on the beach with his school friends.

Teased constantly by classmate Takagi-san, middle-schooler Nishikata swears payback by trying (and failing) to give her a dose of her own medicine.