Leader of the 7th Division and one of the antagonists of the series.
Tsurumi has an unpredictable, mildly histrionic and erratic behaviour. However, In the past, Tsurumi was normal and was even a brave Japanese officer who fought at the front during the Russo-Japanese war.
Receiving a shrapnel in the head and the general bitterness at the poor treatment his division has received after the war has made Tsurumi psychotic and violent, though some of his manipulative tendencies may have been present even before the injury. He is prone to threatening people and personally inflicting physical injury on his enemies but hides his brutal tendencies under a veneer of sophistication and sympathy. He also genuinely admires the macabre work of Edogai and develops a friendship with him. Tsurumi never becomes angry, but coldly manifests his rage with a brutal gesture, perhaps due to his brain damage.
Tsurumi aims to take over Hokkaido and is very ruthless in his methods. He kills anyone in his way or threatens his plan. He seems to still hold the men under his command in high regard but hates traitors. He has shown a level of care for his subordinates as seen when he tries to get Nikaidou to eat his food and provide prosthetic limbs for him.
Tsurumi is also a very charismatic and manipulative man that can sway the minds of other people with a powerful and explosive speech. As a result, he is not above lying to other people if it is to get what he desires, such as loyal and strong followers.