27 years old, jobless, grad school graduate.
At his first job, he felt despair in society and quit his job.
Lives every day fretting how his life is different from those of his friends.
Chosen as a test subject for the "ReLIFE" experiment, he chooses to go back to being a 3rd year student in high school.

Genius with top grades among all females in her graduating class. Extremely bad at communicating with others.
Has the habit of relying on internet searches when she doesn't know something.

An employee of ReLIFE Laboratories in the support department. In charge of Kaizaki's ReLIFE experiment.
Always cheerful but is a very shrewd man.
He turns his guise into a high school student, and supports Kaizaki as his classmate.

Good grades, and highly athletic. Doesn't like to lose, with a very abrasive personality.
However, this stoic tsundere always seeks to move up in the world, never satisfied with the status quo.

Looks flashy, but has the best grades of all males in his graduating class.
Has a pure-hearted side, and is unfamiliar with romance. Has no athletic skills.

Transferred into 3rd year just like Kaizaki.
Optimistic, one can't tell what she's thinking, or even if she's thinking about anything at all.

Captain of the volleyball team.
Lives at her own pace and is calm, but excels at all sports and has unbelievable strength. Childhood friends with Inukai and Asaji, and the two of them call her "Tama(-chan)".

Quiet and unfriendly, but has a very honest personality.
The type that acts before he speaks.
Tamarai and Asaji call him "Aki(-chan)".

Mild-mannered and kind in personality, he is very affable.
Has high athletic skills. Tamarai and Inukai call him "Nobu(-chan)".