MC got a system that told him to be nice to a cub (ML). ML got some trauma so he's trying to deal with it, he went to a virtual world to heal him from his past. MC managed to help ML let ho of his past. ML didn't have a childhood cause the villain injected him with a suspicious liquid. In the extra, ML and MC went to earth and live a slow life. They had 2 cubs and they are born from an egg. The egg could show the cub emotions. 1 of the cub is sticky to ML. Anyways, ML wrote a diary about his cubs in the internet but no one knows that it's written by the scary marshal. MC eventually find out. ML is a lion beast with wings (bcus of the injection)
It could be "What to Do When I Become a Koi and Fall into the Male God’s Bathtub" The MC and the ML are both playing the same game. The MC plays it on his computer in his "normal" world and thinks it is a kind of love game. The ML plays it in his VR-Capsule in his interstellar world and mistakes it as a treatment game for his mental trauma problem. The trauma came from his childhood, where he was captured my some experimental base. It has the eggs that are showing different colors depending on their emotion, but i think the ML is a white tiger and the MC first mistakes him as a cat when he is in his cub-form. And in the interstellar world everyone has an animal type, the MC is a mermaid.