Onee-chan Activities in a Godless World is a Manga/Manhwa/Manhua in (English/Raw) language, REINCARNATION series, english chapters have been translated and you can read them here. You are reading chapters on ManhwaZ fastest updating comic site. The Summary is
In a world where the concept of God does not even exist, a woman as precious as a "god" has been reborn! In search of her beloved brother, Yukito, the strongest sister goes on a rampage in another world - the myth of the onee-chan has now begun!