Kyoko Marihara, a 24-year-old teacher in Japan, has lost her memory of the past seven years due to a blow to the head, and is now a 17-year-old. 24-year-old Kyoko looks and acts like a different person from the serious, happy-go-lucky Kyoko of her 17-year-old days. She is shocked to find out that she has become the teacher she had always wanted to be, but her students are cheating on her, and she is separated from her parents, whom she loved very much... 私は、誰――？ 　24歳の現国教師・鞠原今日子は、頭を打った衝撃で7年間の記憶を失ってしまい、中身が17歳の状態に。 24歳の今日子は、真面目に幸せに生きていた17歳までの今日子とは見た目も様子もまるで別人。 教師という立場でありながら、生徒とは不純な関係で…。 この7年間に、一体何があったのか。今日子は自分を取り戻そうとするけれど…!?