|“||I'd like to watch Four-Eyes a little more. To me it seems... there's something a bit different about him all of a sudden.||”|
Tsutsumi is a light-skinned, moderately tall young man of medium build. He has short, spiky hair styled in a buzz cut with long sideburns and eyes so narrow that they appear to be always closed. His lips are often curved in a faint smile, giving him a kindly, approachable air. He has been seen wearing a zipped jacket over a black shirt as part of his casual clothing.
His unit's uniform is composed of an olive green jacket with black lines around the hem, the zipper, and the high collar, and white ones running along the outer side of the sleeves and around the middle of the collar. There are two piped patch pockets closed by the same flap on each breast, and the B-rank logo is emblazoned above the left one while Border's is located on the outer side of both sleeves a little below the shoulders. The uniform also includes headphones that Tsutsumi wears around his neck, an azure striped shirt with a round neck, grey pants, a black belt with a dark grey pocket on the left side, and dark grey boots with black spats.
Tsutsumi is a calm and congenial person with a penchant for friendly bets. He is tidy, perceptive, considerate of others, and does not hesitate to reflect on his mistakes in order to ameliorate himself.
The members of Suwa Unit have a good relationship and hang out together outside of Border duty. Despite his penchant for gambling in battle, Tsutsumi trusts Kōtarō Suwa, whom he calls by surname, presumably out of respect, even though they speak casually to each other otherwise. Tsutsumi similarly addresses Rui Osano by her surname, whereas she uses a nickname for him, and calls Hisato Sasamori by his first name.
Tsutsumi and Kako are on good terms. He addresses her by surname followed by the diminutive suffix -chan. He often volunteers to try out, her experimental fried rice dishes out of curiosity, although he has gotten sick on two occasions.
Tsutsumi appears to hold the Perfect All-Rounder in high esteem in terms of sniping and mentoring skills. Like the rest of his unit he refers to Kizaki by his first name, which suggests familiarity.
Tsutsumi is very impressed with the three original fighters of Tamakoma Second. Although he admires Yūma's skill and speed, Osamu's tie against Sōya Kazama left an even more lasting impression on Tsutsumi, who has taken to observing Osamu with interest. He refers to the latter by the nickname "Four-Eyes".
- (To Kōtarō Suwa) "I'd like to watch Four-Eyes a little more. To me it seems... there's something a bit different about him all of a sudden."
- "He's fast! But we already know that you can move like that."
- "When an Attacker has a hand free I should always assume it's a trap!"
- (To Suwa) "He's seeing through our attacks. It's like we're fighting against a really good human...!"
- Tsutsumi likes Japanese sake, takowasa (an octopus snack had with alcohol), and historical fiction.
- He has a driver's license.
- The author joked that if Tsutsumi opened his eyes, Border's Hottest Men Ranking would change.
- Due to the frequency with which he feels ill after trying out Kako's fried rice, Ashihara described their relationship as "suspect" and "victim".