Years ago, during elementary school, Kirio and Guest were inseparable friends. Before they became close, Kirio lived his life being ignored at school. Then one day, Guest approached Kirio with a smile, and from then on, they became best friends. Their happy days were short-lived; because Guest was close to Kirio, other children stole a precious family heirloom from Guest. Hearing this, Kirio approached the children and asked for the item back, but they wouldn't give it up easily. As if he had expected this, Kirio handed the children a small robot device, and the moment he pulled out a button and pressed it, the device exploded, leaving the children bleeding and wounded. Of course, Guest's item was also destroyed in the blast. Some children were even brutally killed by the explosion. However, as if it didn't matter to him, Kirio presented the broken item along with his own severed pinky to apologize to Guest. Seeing this, Guest left the scene with a look of loathing and disgust, and Kirio was left feeling excited by that expression. After that, Guest quit school, and Kirio never saw them again.

Ten years have passed, and Guest, now an adult, hosts a masquerade ball for the gathering of noble families to mark their succession. Being a ball, it is grand and luxurious, filled with famous or influential families wearing masks and mingling in small groups as if enjoying a party. Guest, unfamiliar with such settings, wanders around alone. Perhaps having wandered too much, Guest eventually ends up in a deserted area. Guest turns to head back. At that moment, the sound of footsteps approaches from ahead, as if someone had been waiting. Slow and leisurely.