in the years that dazai was on the run, chuuya met and saved a Brown bandaged cat that wouldn't leave him alone.

The cat is suicidal like his former partner which make him worry that dazai antic are contagious and like to drown in water , he's a moocher and no matter how many times he tried to get rid of him because the mafia isn't a place for animals, he always came back.

Then when he had his reunion with dazai he became weirder than before, he don't know what is dazai problem with his cat :

Dazai and nyazai are in a competition for chuuya affection, when chuuya will cuddle him nyazai will always look at dazai smugly to dazai annoyance especially because no one believe him.