The human race, which was thought to have gone extinct after an unprecedented catastrophe, has been resuscitated by the Operators and the memories stored in the Cytus.
Relying on memories stored in the Operators, humans started rebuilding their world - a world where humans and androids live together.
The Cytus, where the memories are stored, is an extremely secret compartment that only certain individuals can access.
One day, the main character wakes in a pod. Looking around, she sees that she is in a laboratory. However, she doesn't remember a thing about her identity, and doesn't know her own motives. In her clouded consciousness, a shadow moves across her vision. Chasing after the shadow, she sees a terminal with "Cytus" written on it.
The main character accesses the Cytus, and starts to recover her memories through music."
A person that was frozen right before the catastrophe. She looks young, but as the one managing the memory data of Cytus, she has maintained her talent despite being mentally old. She shows a cooperative attitude to the memory-less protagonist.
A rabbit-like robot that claims to be MIU’s caretaker. He is able to speak and understand human words, however he is a little childish. He loves the name Omochi, which was given to him by MIU.