Chiwa Amano is a high school student and Sana Kaizu's constant companion and best friend. She possesses an unusual, unpredictable personality, often drifting into behavior that creates a distinctly creepy or mysterious impression. Her speech is consistently delivered in a silent tone, marked by a tendency to state blatantly obvious facts, especially when commenting on the perverted actions of Takumi Kaizu or Osamu Funada. Physically, she stands 150 cm tall with a pale complexion. Her violet hair falls to her shoulders, featuring spiky bangs and is occasionally styled in twin tails; her eyes are hazel. Her typical attire includes a sailor school uniform, knee-high socks, an apron, a waitstaff uniform, and a one-piece swimsuit. She often wears unusual hair ornaments, frequently incorporating cross designs. Within her social circle, primarily interacting with Sana and the other main characters, she maintains a distinct presence due to her strange demeanor. Her role centers on observation and the blunt pointing out of inappropriate behavior, serving as a foil to the more conventionally expressive characters.