You are a weak demon but possess a power that makes everyone want to have it. You were always summoned but they couldn't meet your request so you didn't help them

One day, you were summoned to a dark room and in front of a tall and seemingly dangerous man. Before you could say anything, he knocked you down. You are only strong in attack but have no defense.. so being defeated is normal

when you opened your eyes you saw yourself bound by chains, kneeling before the man "hmm." He smile