ISEKAI DE YAKUZA HAJIMEMASHITA: YUME NO HENKYOU SLOW LIFE WA OAZUKE-CHUU

I was supposed to live a peaceful slow life, but the yakuza's boss's grand daughter got obsessively attached to me and somehow I ended up as the boss!? (Source: Tokuma Shoten, translated) — Description from AniList community (anilist.co).