Park House 

Chanyeol and baekhyun been married almost 5 years now but after chanyeol got into car accident he lost all his memories but he only remembered his parents and sehun. After that chanyeol's mum kicked out Beakhyun and suho. They travelled to China and cut their contact with park's family including sehun and his family.

In China 

Beakhyun had already found a job there. She enrolled suho to elementary school. There Beakhyun can not use park here so she changed her daughter's name to byun suho.

When they arrived at school they saw familiar faces which sehun and his family here. Turn out that sehun has business here and he decided to bring his family with him since his son upset because his favourite cousin away from him. Suho and chen have same class.

In the class 

Suho and chen sit next to each other but they need two more person cause one table has four chairs. A lot of kids doesn't want to sit with them. When the two last (xiumin and luhan) person came they sit with them.

Explain xiumin 

Her parents just like chen they have business there too. Kim company with Park Company.