Aoi Yuu is a high school student who has just transferred schools because of her parents' remarriage. Her new school is a prestigious "all-boys" boarding school where students who have memories of the loyalists from the Edo bakufu era go to.

After meeting her roommate who has the memories of the Shinsengumi's Hijikata Toshizou, she began to recall the memories hidden with her...!? And thus begins her secret school life!