The puppy I found turned out to be a Cerberus! ~A boy who is actually a user of ancient magic lives happily with his beloved dog, who can be scary when he gets serious (?)~

拾った子犬がケルベロスでした～実は古代魔法の使い手だった少年、本気出すとコワい(?)愛犬と楽しく暮らします～