I'm still kinda confused what is bro cheng business?!

anak siya ng mafia boss jkjk

It's kinda implied that the He family is a whole mafia, along with Jian Yi's father side of the family. (In earlier chapters you can see that He Cheng works for Jian Yi's grandfather)

so in short the HE family is more likely an underlings to Jian Yi's grandpa?!