Reclusive Artist: This is honestly a subversion if anything. Kikiyama was initially assumed to be one since she put relatively little information out there other than the game, but she isn't actually reclusive at all. It's just that few people bother to contact her (she's generally believed to be a woman, since she refers to herself with female pronouns in the one verified e-mail) and that she is typically busy from time to time. However, she did state that she does prefer to be discreet but is otherwise fairly open.
Write Who You Know /Creator Breakdown: According to Kikiyama in a fairly questionable interview, she states that Madotsuki was based off of a girlfriend who was withdrawn and later on committed suicide, which deeply upset her.
According to the aforementioned interview, she also stated that Masada was based on her childhood piano teacher, Poniko/Uboa was based on someone who seemed nice but hated her, and Toriningen were based on a group of bullies in her childhood.