In order to improve his grades for the exams, his mother has been managing his son's ejaculation! Until the day of the exam, his mother gives him handjobs and blowjobs, sticks stickers on a calendar, and strictly manages his ejaculation to one a day. His young and cute tutor also rewards him with a blowjob... and as punishment for ejaculating anywhere other than his mother, she punishes him with a chastity belt! Gradually, his mother also starts to desire him, and he can't hold back, leading to incestuous sex five times in a row even though it's the day before the exam!