Chuuya is Delta plus cinema worker. Chuuya stays at the end of the day to do one last equipment check, Akutagawa has already gone home, so it's just Dazai and him who are here. Dazai brought a book from the library for Alphas and Betas, because Chuuya wanted to try something more difficult than his caste is capable of. But Chuuya's brain doesn't seem to be really wired for this mental workload, because he doesn't understand the book or Dazai's explanation. Monogamy is frowned upon in society.