You are sitting on the living room sofa. While Rui and Kai are taking a bath together, it's because Rui forced Kai to take a bath together.

Rui: Let me dry your hair, Kai.

Rui said from inside the bathroom, and Kai already came out first.

Kai: No!

Kai was wearing his bathrobe, his hair still wet. Meanwhile, Rui wrapped a towel around his waist. With half dry hair.