Congratulations! My Wife Is Pregnant with a Monster

In this town, there are many happy families. When Kazuya learns that his wife is pregnant with their second child, he decides to return home after working away for some time. Excited to reunite with his family, Kazuya opens the door to find a monster covered in hair sitting in his home! The creature has huge claws and fangs, but his daughter runs up to it, calling it her "friend." They all eat together with the monster as if it's completely normal. Is Kazuya the only one who finds this crazy? And his wife... she was "given" something by the monster... rubbing her belly... does that mean the baby in his wife's belly is...?!