The Eminence in Shadow

Cid is the eighth-grader version of every reader who has ever fantasized about being the secret mastermind in a fantasy novel. His self-styled organization Shadow Garden is supposed to be elaborate chuunibyou. The cult he invented to give the organization an enemy was supposed to be made up. The first season is what happens when both turn out to exist — the cult is real, his Shadow Garden recruits genuinely believe him, and Cid spends the run improvising authority while assuming he is still the only person in the room who knows he is playing a part.