Koi Kawai is a ponchopal, a species designed by Sleepygrim on instagram https://instagram.com/p/BVLlkxTjrZI/
Koi is Dooms pet/ friend and she ends up living with Doom in his house :3 (Doom loves her a lot and made her a poncho that looks like his shirts)
Koi's island/ universe in her poncho is mostly water with many kinds of fish. I imagine it with mostly shades of blue and orange, occasional other colors exist.
I will work more on her personally in a little bit, and will update it here later.
This sketch is downloadable for me and anyone who wants to draw her and needs a ref. Feel free to download.
Sleepygrims guide to ponchopals for those without instagram: http://app.sketchclub.com/sketch/10852994