花は求職活動中の25歳。突然の親戚からの依頼で、不登校の従妹・16歳の替え玉として学校に通うことになってしまった！ 見た目もソックリでバレないはず…と潜入した登校初日に､なんと高校の同級生・蟹江が先生として現れて､ソッコーでバレてしまう｡黙っててほしい、そうお願いした花に、蟹江からのオトナな指導が始まって…！？
Once most students are done with high school, they leave and never come back. However, at 25 years old, Hana Natori finds herself in the role of a student once more at her aunt's request.
Since Hana's cousin, Kaho Miyoshi, refuses to go to school, her aunt begs Hana to take Kaho's place, since the two of them are practically identical. But as luck would have it, she is recognized by Okito Kanie—an old classmate from her days in high school—who is now a teacher! With her cover blown, Hana assumes Kanie will expose her secret. But when he suddenly kisses her, she soon learns he has other ideas.
[Written by MAL Rewrite]
