When at least two versions of the same person from different alternate universes meet.

Individuals who passed away before achieving their dreams, now residing in the Void World for a limited period. They have no memories of their past—only a sense of familiarity with their surroundings and knowledge of their own name.

Twins who have entered the Void World. Their duty is to help the deceased remember their past before their time runs out, allowing them to rest in peace. They require the assistance of well-trained Clock People to navigate the Void World safely.

Entities born as proof that the "Twins" are one. Initially emotionless, they possess immense, unstable power. Through training, they gain control, marked by a clock manifesting on their body, signifying their readiness to enter the Void World. 

Mystical beings responsible for maintaining balance in the Void World and White Space.