Korosazaru Mono, Ikubekarazu

Amahiko Sakurai and Yukio Higashi. A promising young psychiatrist and a leader in an unprecedented large-scale terrorist organization. Best friends who once laughed together. Since the mysterious death of Amahiko's older brother, when the two have taken different paths and reunited in the opposite positions of an expert witness and a suspect, the two destinies meet, merge, and despair quietly opens...

(Source: Kodansha, translated)