Yakuza Fiancé - Raise wa Tanin ga Ii

Yoshino has always been treated differently because she is the granddaughter of Osaka's biggest mafia boss, so everyone is afraid of her, and she has never ever had a boyfriend. One day, her grandfather tries to arrange an engagement for her with a boy of her age, Kirishima who is intelligent, calm and kind and the grandson of another great mobster. In spite of everything, she decides to go live with Kirishima in Tokyo and begins to take an interest in him, but what will she do when she finds out that he is not only part of the mafia but is also a masochist? (Source: Mangamonster.net)