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

Hinoharu Kota is newly married but his wife is never home. Bored, Kota imagines being on a relaxing ski trip to clear his mind. In his "dream" everything goes sideways. Still dreaming, Kota walks through a couple of doorways to shockingly find himself springing into action to save a female knight from a giant spider. Kota discovers he was "summoned" to this other world as something known as a summon beast, a helper that can be transported from his earth to other realms. As he completes these summoned missions as a summon beast, he can gain magical powers and abilities. As a man without any special skills on his own earth, this might be the best thing that has ever happened to him.

(Source: Mangamo)