Blood Moon Questions

A friend of mine said that the blood moon skins- which all look awesome by the way way to go Riot, were based on the Oni. However when I attempted to google them I found many different versions of them and even fewer that seemed to have influenced the idea of the skins. So I was wondering firstly if it is true that they really are based on the oni, and if so what kind, and thirdly if the skins aren't based on the oni what might they be? (I'm sorry if I spelt oni wrong, or if it's meant to be capitalized. Also if this does relate to anyone's religion, this was a quick google search please keep that in mind, I'm very sorry if in any way I may have offended you.) Thanks in advance.