Shion is the main protagonist of the story. When she was five years old, Shion's parents were slaughtered in their own home, though the murderer was never found. Shion, being a young girl at the time, was traumatized by bearing witness to the aftermath and since then has not spoken one word. To communicate, she writes down everything via notes. At the murder scene, Shion found a king shogi piece and later comes to suspect that the culprit plays the game.

When the story begins, Shion is eleven (in the manga) and is in junior-high school. She loves sweets, though chocolate is her favorite. Due to her foster father's influence, Shion eventually starts to play shogi which she hopes will give her clues about the murder of her parents.