Kekkon x Renai.

Shiho is an unfortunate woman. Her marriage only lasted for three days because of her husband died. Shiho then decided to be the guardian of her late husband's little brother, Makoto, who was still in elementary school. Nine years later, and it turned out Makoto is actually the one who's been taking care of Shiho. On his eighteenth birthday, Makoto asks Shiho (age twnety-nine) to take responsibility and marry him.

(Source: MU)