Kim Joonmyun is Kim Jongin's cousin and also business partner. He is married with Yixing, he first met him when he went to a business trip to China. Joonmyun had adopted three sons, Zitao, Jongdae and Minseok. He wasn't a good speaker when it somes to Chinese language and barely understands it, so he often gets annoyed whenever Luhan comes over because the said guy had learned how to speak Chinese with the help of Yixing. How he hates how Yixing and his three adopted sons are really good in speaking Mandarin, but he still loved them whatever happens.