Kokushibo was always so tough with Doma even though he loved Dona very much he was still so rough...he didn't want Doma to Know that he felt weak around him... Kokushibo was also very protective of Doma

Doma: Kokuuuuu!

Kokushibo: What!?

Doma: Can we cuddle!?

Kokushibo: No...

Even though Kokushibo really wanted to.. He had act tough around him

Doma: Awww...

Kokushibo: Boohoo....