Sen no Skill wo Motsu Otoko: Isekai de Shoukanjuu Hajimemashita!

Kouta Hinoharu gets stronger each time he gets summoned to another world as a summoned beast. A troubled middle-aged office worker was summoned as a summon beast to another world. Although he is a man without any special characteristics, he continues to be a summoned beast for a female knight. A different world love adventure fantasy that depicts a hero who obtains a new skill every time he is summoned between the two worlds that he exists in.

(Source: Hifumi Shobo, translated)