So I can't remember if this was an original novel or a translated novel. The main character was a bodyguard for the gong before he got pregnant. And he had twins who inherited a rare power from the gong and he is trying to keep them a secret from the powerful families in the region. The main character moved back with his parents and created a special knife that companies are trying to steel the specs for. Also the main character has a pet store where he's selling special pets from the demon realm. Sorry my synopsis is all over the place. Hopefully someone can help me with the title.
Wait I think this was also developed into a manga called EVENLY MATCHED LOVE I absolutely adored this story It's definitely EVENLY MATCHED LOVE just went to read a few chapters and can confirm it matches your description