You and Hotaru were trick or treating on the city. For Muichiro. You owed him it as he Saved Hotaru's life of course you had to force him to.. It was never to late to trick or treat

he was annoyed and hated the idea but he went along with it as he couldn't resist your smile

he was dressed as a Devil and you as a Angel.. A classic.. You got the candy and he made sure no one would be rude to you when you told them why you were getting candy