Responses
No, Shuu is only Riku's father (Misaki's kid). Kouga's father is Kazunari (the one with the butler on the car near the end in ch 4) while his mother, Masato, is the omega Shuu rescued (seen on the panel where he was holding out an umbrella to a person). Hope this helps! ヾ(☆▽☆)
wait im confused so shuu who took in misaki as a kid and had a baby with him is kougas father??