Nobunaga-Sensei No Osanazuma.
The manga focus on the relationship between a middle school teacher Nobunaga, who love women's sports and a 14-year-old "perfect wife-to-be" an expert on the Sengoku period.
"One day, a girl who loves me will show up" Nobunaga has been dreaming of such a situation.
However, the one who showed up before him was Kichou, a 14-year-old girl who declares herself as his wife.
She seems to have been transported from the Sengoku era, mistook him for Nobunaga Oda and urges him to have a child with her.