Isekai Yakuza: Gokudou desu ga Teni shitara Kyuuseishu ni Narimashita

During a gang conflict, Ryuuto Aigou, a yakuza member, is caught in the blast of a rocket launcher and unexpectedly transported to a different world. By chance, he saves an elf girl from goblins and is hailed as a hero. In this new world, various monsters like orcs, harpies, slimes, and dragons vie for dominance, reminiscent of yakuza turf wars. Ryuuto decides that if he's going to be here, he might as well aim for the top! He establishes his own crew and embarks on a wild, action-packed adventure as the most formidable yakuza in an unfamiliar realm.

(Source: Taiyo Tosho, translated)