Kekkon suru tte Itta yo ne?
結婚するって言ったよね？
As a child, Hiro made a promise to Mana that he would marry her once he turned 18. However, after witnessing his father's frustration with family life, he changed his mind about marriage. Years later, as he begins his final year of high school, Mana has become increasingly erratic, constantly pressuring him to fulfill his childhood vow.