Oikawa not accepting the truth, while accepting a seemingly wild as it seems "lie" about something indeed secret going on with professor along with other elders, just like typical conspiracy theorists...
Wait, what? Kei was wearing a wig all the time, thought he grew his hair?!?
Him going back to his previous self while being a trap and talking with Yuu, but since she knew about him when they visited Okinawa that she looked like him, went back to his previous looks... K... odd...