25-sai no Joshikousei 2

When her 25-year-old cousin, Natori Hana, refuses to attend high school, Natori Hana becomes enraged. Hana assumes her cousin's responsibilities and enrols in high school in her place. But on her first day, Hana's trick is uncovered by Kanie Akito, who happens to be the high school's global history teacher and a former classmate.