ninkyou tensei

Yakuza Reincarnation, also known as Ninkyō Tensei –Isekai no Yakuza Hime– (任侠転生 –異世界のヤクザ姫–) is a manga series written by Takeshi Natsuhara and Hiroki Miyashita and illustrated by Miyashita. It is a genderswap isekai manga about an old yakuza man who dies and wakes up in another world in the body of a young princess, retaining his back tattoo and strength, and rebuilds the princess' territory with yakuza chivalry.