Like the other intermission “quests” before the big main quest, this will just require you to change out of costume and turn in for the night. Simply head to your bedroom and loot the rewards you haven’t claimed yet in your toybox. Head to bed but then your mom will tell you to get your dinner downstairs since she forgot to give it you. Go downstairs and eat your dinner then head for bed again. Mysterion will call you so switch to your costume for the next main quest.