Yamaokusodachi no Ore no Yururi Isekai SeikatsU: Mofumofu to Saikyou-tachi ni Kawaigararete, Nidome no Jinsei Mankitsuchuu

After saving someone and losing his life, Yuuki is reincarnated into another world. He wakes up as a baby in the middle of a blizzard in the mountains?! Facing a dire situation, Yuuki prepares himself for death, but thanks to the one power bestowed upon him by God—a strong body—he's able to easily navigate snowy mountains!? He's also picked up by a kind family, showered with their love, but in reality, his parents are legendary figures, and Yuuki has grown into an extraordinary man! "I want to leave this mountain, and return it to the way it was loved by my mother and children!" Now six years old, Yuuki decides to set out on a journey with his beloved dog, Pochi, to become independent! He faces many challenges along the way, but unwittingly overcomes them with his cheating skills!? What started out as a leisurely journey quickly becomes a source of rumor throughout the kingdom...?!

The start of an unconscious and extraordinary fantasy adventure in another world, unfolding as the strongest child raised deep in the mountains unfolds!

(Source: Starts Publishing, translated)