Isekai Yururi Kikou: Kosodate Shinagara Boukensha Shimasu

a journey through another world raising kids while adventuring - Takumi gets accidentally killed by the wind god Syl and is reborn and summoned to another world. After giving Takumi his sincerest apologies, Syl grants Takumi with skills and sends him to the world Etelldia that Syl presides over. However, this new world is a vast forest filled with dangerous monsters... In the forest, Takumi finds a young boy and girl who appear to be twins. He is worried about their safety and names them Alan and Elena, and decides to take care of them. He soon finds out to his surprise they are able to defeat a monster with their bare hands. The three of them reach a town, and Takumi decides to register at a guild to make a living. He begins his life as an adventurer while taking care of the two children. An isekai fantasy about an adventurer with two kids!

(Source: Alpha Manga)