Shiroi Majo - Utsukushiki Sniper is a Manga/Manhwa/Manhua in english language, Seinen series, english chapters have been translated and you can read them here. You are reading chapters on www.mgeko.nl fastest updating comic site. The Summary is

In June 1941 Finland launches an attack to reclaim the territories lost to the Soviet Union in what ended up being called the Continuation War.