Arata est au bord du gouffre quand le mystérieux Ryo Yoake, employé de l’institut de recherche ReLIFE, frappe à sa porte et lui propose de participer à une expérience de réinsertion sociale, qui passe par… une année de retour au lycée ! Le jeune homme n’a rien à perdre. Il avale la pilule qui lui redonnera l’apparence de ses 17 ans et reprend le chemin de la terminale. Sa nouvelle vie d’adulte parmi les ados commence…

Arata meets Chiziru Hishiro, a girl who has zero communication skills but is trying her best to change.

Arata receives a grim reminder of his physical age during athletic testing.

Rena Kariu is thrown for a loop by what she thinks is Chizuru's spiteful behavior toward her.

Things come to a head between Rena and Chizuru, which reminds Arata about a traumatic experience in his past.

An Onoya and Kazuomi Ooga suddenly visit Arata for a study session, after which An puts the moves on Arata?!

Ryou reflects on the year before and his failure supporting test subject no. 001

Honoka is distracted by her troubles and inadvertently causes an injury to Rena.

The rift between Rena and Honoka grows ever larger as the former decides to retire from high-school volleyball, but Chizuru and Arata decide to fix things.

Things come to a head as Chizuru and Arata decide to confront Rena over her behavior.

Arata decides to visit a grave and ends up taking a trip down memory lane.

Arata, once and for all, tries to make the dense-as-can-be Kazuomi realize what he has in his hands.