Hokuou Bishoujo no Classmate ga, Konyakusha ni Nattara Deredere no Amaama ni Natteshimatta Ken ni Tsuite

"Renjou-kun, I want you to be my fiancé." Tooru Renjou, who, at a bookstore, helped Aino Luthi—the Nordic beauty renowned as the school's cutest— is suddenly asked to become her fiancé. At first, it was merely a request to avoid an arranged marriage, but once Aino learned that her partner is to be Tooru, she suddenly becomes eager for the marriage…!? This is the story of two people who were supposed to be only fiancés for the sake of formality, but who gradually come to understand each other and eventually become true lovers. (Source: Hifumi Shobo, translated)