25-sai no Joshikousei

Twenty-five-year-old Hana Natori agrees to an unusual request from her aunt: impersonate her nearly identical cousin Kaho, who refuses to attend school, and take her place in class. The plan seems possible as long as Hana can convincingly behave like a high school student, but the first person to recognize her is Okito Kanie, an old classmate who is now a teacher at the school. Hana expects him to expose the deception immediately. Instead, he keeps her secret for deeply personal reasons and begins pursuing a relationship tied to feelings left unresolved from their own school days. Caught between maintaining the disguise and keeping both school and family from learning the truth, Hana finds herself living a strange second version of high school beside someone who knows exactly who she really is.