Hai to Gin no Hane

In the year 3215, all domestic fighting has ended and a peaceful winter has come to the world. Veteran Kirjaska Leino meets former child soldier Mjeli Haltonen, who has only ever known the battlefield. Kirjaska ends up taking care of Mjeli, who has nowhere to go, in exchange for being provided with a place to stay, and they begin living together in a small house in the forest... The two, who have lost their way, live a peaceful life together in the snowy country.

(Source: Natalie, translated)