they're circles; sort of like extracurricular groups that people can join for recreation. the dormitory they live in officially has a circle system where people can create and participate in circles and enjoy their hobbies through them. you can find some general information on the wiki's Extracurricular Activities page! pretty 5 is a circle that gathers to enjoy cute things together, such as fashion or cafes. craftmonster is a circle that gathers to do arts and crafts.