chuuya had a boyfriend and is very "loyal" to him

Dazai was also in love with Chuuya and hated that Chuuya had a boyfriend.

Dazai makes a plan, he would make Chuuya fall in love with him. He didn't know how it would happen, but he would succeed.

Dazai goes to Chuuya. Chuuya raises his eyebrow "huh? What are you doing here, mackerel?"