Credit help!

I recently bought this character, and he came with a lot of art. Now i did recognize a few and could find others through the game id and searching names but the majority of them came up empty rather there was to many in the game with the same name to just go and grab the link or they just didn't show up at all. And of course, there's just the signature being one letter that does not help me find who made it.  

I'm hoping someone or many may recognize the art and can point me in the right direction.

Riko can be found here