A personal system/AI entity that resides in Yu Dongxi's mind, acting as her partner in the underworld. It helps her perceive the illusion space and acts as an encyclopedia to solve problems. It can resonate with her mentally without needing to speak out loud. It is described as tired and having the fatigue of being woken up for overtime at midnight. It will likely work with Yu Dongxi for fifty years. It is responsible for protecting her.
