TV-Series
Description
Hajime Tsukishima was born on Sado Island, where he grew up as the son of a father widely detested by the locals. Known as the "murderer's son," he frequently engaged in fights. His only friend was a girl with wild, unruly hair nicknamed Igogusa; she was the only person who called him by his name, Hajime.

As a young man, he enlisted in the 2nd Division out of Shibata and fought in the First Sino-Japanese War. Before departing, he promised Igogusa he would marry her and leave the island together after the war. Upon his return, however, he discovered that rumors of his death had spread and that Igogusa was missing, with only her shoes found on the shore. Believing she had killed herself, he traced the rumors to his father and killed him in a rage. He was arrested and sentenced to execution for parricide.

In prison, he learned Russian, both from Tokushirou Tsurumi and independently, alongside Hyakunosuke Ogata. In 1896, Tsurumi visited him, investigated Igogusa's disappearance, and claimed she was still alive, presenting a lock of her hair as proof. Tsurumi recruited him into the 7th Division, secured his pardon, and had him released to work as an interpreter.

In 1902, he was dispatched to Fort Goryokaku in Hakodate to assist in the kidnapping of Otonoshin Koito. He participated in the Siege of Port Arthur, including the Battle of 203 Hill.

During the 1905 Battle of Mukden, a soldier from Sado informed him that Igogusa's body had been found, exposing Tsurumi's deception. He confronted Tsurumi violently but protected him during a Russian bombardment, sustaining injuries. After treatment, Tsurumi explained the full story of Igogusa and outlined the Ainu plan. Tsukishima pledged his remaining life to Tsurumi's service.

He first appeared narratively with Captain Wada, whom he killed on Tsurumi's orders after Wada confronted Tsurumi. In Yubari, he staked out a grave to catch a grave robber, later discovering the tattooed corpse was missing. He monitored Edogai's taxidermy shop, enduring Edogai's tantrums. After forgetting his wallet, he returned to find Ogata attacking Edogai; he rescued Edogai and fled into the mines, pursued by Saichi Sugimoto and Yoshitake Shiraishi. An explosion trapped Edogai, who died after entrusting Tsukishima with fake tattooed skins for Tsurumi.

He later cared for the wounded Kouhei Nikaidou in a hospital. Often called the "Conscience of the 7th Division," his character embodies Acedia, a state of not caring that empowers evil through inaction, as reflected in his early portrayal as a nameless minion following orders without question.

His interactions with Otonoshin Koito are formal, typically addressing him as "Koito shōi-dono," while Koito calls him "Tsukishima," sometimes elongating it for attention or complaints. Parallels exist between him, Ogata, and Sugimoto. Both Tsukishima and Ogata committed patricide, but Tsukishima's was brutal and personal, while Ogata's was methodical. Unlike Ogata, Tsukishima retained empathy and romanticism from his relationship with Igogusa. His character arc positions him between Ogata's detachment and Sugimoto's struggle for humanity, with his development involving a choice between emotional numbness or striving for hope.

He perceives himself as ineffective in helping others, citing failures such as not stopping Nikaidou's morphine use, failing to save Edogai, and losing Igogusa. He functions socially better than Ogata but remains damaged, interacting from scarred experiences. In the live-action film, the character is portrayed by Asuka Kudo.