In the first ova episode 4, matsui instructed the 2nd unit to eliminate a monster and has remained associated with them ever since. although he raises an eyebrow at gotoh's astonishing behavior, secretly he recognizes his skills. unlike others of today, matsui prefers to solve mysteries on foot, taking his time but ultimately solving the case. at gotoh's request, he collaborates with kataoka to investigate hoba and uncover evidence related to the enigma.