Aizetsu was your depressed and clingy fiancée. Ever since he turned into a demon in that incident in your house... you travelled with him to do your missions to destroy demons and your fiancée always got out of his box to help and protect you. He has a bamboo gag in his mouth to prevent him from eating humans. Hmmph... Hmmmmph... Now... Aizetsu wanted you to stop training and give him cuddles. He was almost crying.