Boogiepop Phantom

Souhei Saikawa is a college professor who is obsessed with genius Shiki Magata’s work. He, Moe Nishinosono, and a group of his other students plan a retreat to the remote island where Magata currently resides, which may put them in danger’s way...

A species of parasitic aliens descends on Earth and quickly infiltrates humanity by entering the brains of vulnerable targets; insatiable beings that gain total control of their host and are capable of transforming themselves to feed on unsuspecting prey. High school student Shinichi Izumi falls victim to one of these parasites, but the creature fails to take over his brain and ends up in his right hand.

A supernatural system allows people to take revenge by having other people sent to Hell via the services of a mysterious entity and her assistants who implement this system. Revenge, injustice, hatred, and the nature of human emotions are common themes throughout the series.

Kenzou Tenma, a Japanese brain surgeon in Germany, finds his life in utter turmoil after getting involved with a psychopath that was once a former patient.