The MC here is a DND bard, he seduces his way through most of the incidents, it is not mentioned much early on and the manga changes a few things, but he gets through half of the story with his looks alone. The girls who work at his ex shop give him a perfect 10 for looks, he seduces everything down to even ghosts. The big joke is that the main enemy who is female will lose by being seduced by him.
As for arm girl, she is the 2nd daughter of the strongest organization in paradise(the organization the one who recruited the MC belongs to). Her stuborness is because she doesnt want to rely on her famiky since she has an inferiority complex with her older sister. She with the help of an employee sneaked into this test to prove her worth.
Thier only similarity is that they share a similar fetish, only difference is she is picky while he goes after anyone biologically female.