First Lieutenant Tsurumi is the leader of a corrupted platoon of the 7th Division, he and the soldiers loyal to him are looking for the hidden gold, which makes them competitors to the protagonists and one of the main antagonists of the series.

During the war he was wounded to the head, which took away from him a part of his brain.

Tsurumi is an Intelligence Officer, which sets him apart from other military officials for his ability to analyze and manage informations on a wide scale.

He resents the unsatisfactory treatement the soldiers received after sacrificing themselves and their comrades on the battlefield of the Russo-Japanese war, the sentiment is shared by many other soldiers in his division. Tsurumi in particular was critical of the responsibility the higher officiers had in the number of casualities during the war.

(Source: Golden Kamuy Wiki)