Amnesia Syndrome is an infectious disease identified in the 21st century.
It is a virus that violates nerves in the brain. Those infected with this disease gradually lose awareness of the boundary line between themselves and other people. Ultimately they lose all awareness of their memories and it ends their lives.
A large number of people have been infected, yet it still remains unclear how infection occurs. According to one theory the infection spreads through the collective unconsciousness of the people.
In 1970, a treatment was being developed by a certain scientist, however he died and the research remained at a standstill for many years. In 2030 a vaccine was developed.