Tsukishima is a short but thickset, muscular man, with dark hair shaved in a buzz cut, dark eyes with a slight greenish tint to it, and stubble on his chin. His most significant physical traits are the two lines under his eyes and a short flat nose that he inherited from his mother. Just like the rest of the 7th Division soldiers, he wears the standard Japanese military uniform and a hooded coat over it.
Tsukishima has a scar on his abdomen that he received while protecting Tsurumi from an explosion during the Battle of Mukden.
Tsukishima is a very serious man, known for being diligent and dependable. He dutifully takes orders from his superiors and is unfailingly polite to those of higher rank. Though he is aware of the First Lieutenant's trickery and devilish ways of manipulating others and himself, he is shown to be extremely loyal to Tsurumi. Tsukishima considers himself to be a man whose life has little value. After spending many years assisting Tsurumi in his plans, Tsukishima believes that he is too far gone, so there's nothing left for him but to do his job and watch Tsurumi's plans unfold.
He is brutal and efficient in a fight, willing to put himself into the fray and end the conflict as quickly as possible, whether that means kicking an animal off of his superior's back or just throwing bombs to clear out as many people as physically possible. By Tsukishima's own admittance, he is willing to dirty his own hands in order to get the necessary results that he desires.
Because of his stoic demeanor, Tsukishima often has to act as the straight man as the rest of his group crumbles into chaos around him. Despite that, Tsukishima has shown to care for his comrades, as seen when he offered words of consolation to Genjirou Tanigaki who had been verbally reprimanded, and continued to show concern even when he was unable to address others directly.
- Physical power: Despite his humble height, Tsukishima is a dangerous opponent to face in close combat. He has a lot of stamina and endurance, which allows him to go on even when gravely injured or intoxicated with poison. He has a lot of strength in his lower body and prefers to attack his foes with kicks in hand-to-hand combat.
- Russian language: Tsukishima is fluent enough in the Russian language to hold conversations with native Russian speakers. However, he is not proficient enough to translate difficult expressions.
- Marksmanship: Tsukishima is skilled with a rifle and is able to shoot well.
- Arisaka Type 30 Rifle (holds five rounds)
- Tsukishima's name contains the kanji:
- (月) Moon
- (島) Island
- (基) Basement, first
- Tsukishima likes egoneri (boiled egogusa seaweed) and white rice and dislikes nothing.
- In 2018 Golden Kamuy All-Stars popularity poll, Tsukishima ranked 3rd, gaining 9,851 votes. 
- Tsukishima enjoys taking long baths.
- Tsukishima is shorter than Kantarou and the Nikaidou twins, and taller than Henmi, Inkarmat, and Anehata.
- Tsukishima is lighter than Nihei, about the same weight as Sugimoto and Vasily, and heavier than Tsurumi.
- Tsukishima is older than Shiraishi and Inkarmat but younger than Kikuta.
- According to Satoru Noda, Tsukishima has one of the "juiciest" asses in the manga; the other listed characters are Tanigaki, Shiraishi, Ariko, and Usami. 
- Tsukishima's village is likely based on Shukunegi village, located on Sado Island, Niigata.
|First Lieutenant||Tokushirou Tsurumi|
|Second Lieutenant||Otonoshin Koito • Yuusaku Hanazawa ☓|
|Warrant Officer||Mokutarou Kikuta|
|Superior Private||Hyakunosuke Ogata ☓ • Tokishige Usami|
|Private 1st Class|
|Allies||Heiji Koito • Hidenobu Okuda • Narizou Arisaka • Teruchika Yodogawa • Yasaku Edogai|
|Associates||Kouji Wada• Koujirou Hanazawa|
|Main Group||Asirpa • Saichi Sugimoto • Yoshitake Shiraishi|
|Former Members||Cikapasi • Fusatarou Oosawa • Genjirou Tanigaki • Inkarmat • Kiroranke • Retar • Ryu • Vasily|
|Associates||Hajime Tsukishima • Hyakunosuke Ogata • Otonoshin Koito • Tatsuma Ushiyama|