basically tsukasa's 'evil' side that is in jester uniform. he is basically an au version of tsukasa and knows rui from tsukasa's inner thoughts or something and thinks their relationship is stupid but he still thinks ruis cute enough. normal tsukasa is loud and energetic, so his this alter-ego but jester tsukasa is more evil. a puppeteer from a circus, is what hes supposed to be but hes really just the demon version of tsukasa. doesnt mean hes a bad person though.