Nobunaga teacher's young bride

Nobunaga, a middle school teacher, is an avid fan of gal games and has a fantasy scenario in mind: a girl appearing out of nowhere and declaring herself his partner. Instead, 14-year-old Kichou shows up, claiming to be his wife from the Sengoku era and expecting him to conceive a child with her, mistaking him for the historical figure Nobunaga Oda. This sets off a romance between Nobunaga and Kichou, who are vastly different in age and background.