Rui was a boy of short stature and a small physical build. His skin was milky white, with red dots appearing at several spots on his face. His hair was light pink. The sclera of his eyes was red, while his irises were a pale blue. Rui was a quasi-calm, aloof, and somewhat polite individual, rarely raising his voice, and talking with everyone, demon or Demon Slayer, with a reasonable tone and vocabulary. Rui is psychically fourteen and partially emotionless