Name: Kei Tachikawa Age: 20 (University Student) Height: 180cm Likes: Udon, Mochi, Croquettes, Winning Rank Wars Affiliation: Border Headquarters, A-Rank #1 Tachikawa Unit Rank: A-Rank Agent, Captain Title: No. 1 Attacker, No. 1 Overall Individual A young man with messy, light hair and a goatee. His eyes have a grid-like pattern. Notably, he is the only Border agent who uses the Kogetsu dual-wield style. He can cleave a Rabbit—which gives even A-Rank agents trouble—in a single stroke and cut down an Ilgar in self-destruct mode that Ai Kitora couldn't even scratch. In Border, where 10,000 points is considered top-tier, he alone possesses a staggering score of over 45,000. Initially, he gave off a detached, eccentric aura, with Miwa even saying his methods were similar to Jin's, but his primary motivation is being a battle junkie. Outside of combat (academics and private life), he is quite hopeless, gradually becoming more of a gag character. His passion for mochi is stronger than anyone's; he was even stuffing his face with it during lunch right before the Large-Scale Invasion. His only skill outside of combat is grilling mochi on a shichirin. He is Jin's rival, but doesn't hate him. They share a top-tier rivalry where they acknowledge each other's strength.

Name: Kohei Izumi Age: 17 (High School Student) Height: 175cm Likes: Fried Shrimp, Croquettes, Mikan Oranges, All-Range Attacks Affiliation: Border Headquarters, A-Rank #1 Tachikawa Unit Rank: A-Rank Agent Title: Shooter A Shooter belonging to Tachikawa Unit. A young man characterized by light-colored hair and narrow eyes. He possesses top-class Trion capacity even within Border and is a powerhouse who, along with Tachikawa, keeps the unit at the A-Rank #1 spot despite having Yuiga on the team. The author calls him a genius. He is in the same class as Yoneya in high school, and they seem to be close friends who call each other "Bullet Idiot" and "Spear Idiot." He also seems to be close with Midorikawa. During the Large-Scale Invasion, the three of them acted together, defeating Ranbanein through their coordinated teamwork and the help of the B-Rank joint units. He earned a First-Class Merit for this achievement. Since the invasion, he has deepened his friendship with Osamu, a fellow Shooter. While he has been asked to teach composite bullets, he is currently waiting for Osamu to gain more combat experience before starting the lessons.

Name: Takeru Yuiga Age: 16 (High School Student) Height: 169cm Likes: High-end French Cuisine, Being Respected Affiliation: Border Headquarters, A-Rank #1 Tachikawa Unit Rank: A-Rank Agent Title: Gunner A spiteful guy who takes pride in being a member of the A-Rank #1 team. He behaves in a pretentious manner, often seen flicking his bangs with his fingers. He has a personality with intense emotional ups and downs and frequently gives exaggerated reactions. Basically, he's loud. Despite being aware that he is weak, he hates losing, making him a very high-maintenance person. When Izumi suggested to Osamu that he would teach him composite bullets if Osamu could win 100 matches against Yuiga, Yuiga wailed and refused because he knew he would lose 100 times. As soon as he realized Osamu was weaker than him, he reverted to his usual arrogant attitude, acting like a big shot senior—an annoying guy. On the other hand, while he calls Izumi a "too-strict senior" and complains constantly, he ultimately follows orders, so there is no real conflict. Izumi and the others treat him coldly but don't actively try to kick him out, seemingly keeping him around with a "if you want to be here, stay" kind of affection.

Name: Yuu Kunichika Age: 18 (High School Student) Height: 163cm Likes: Ishikari Nabe, Buttered Potatoes, All kinds of games Affiliation: Border Headquarters, A-Rank #1 Tachikawa Unit Rank: A-Rank Agent Title: Operator Border's No. 1 gamer who loves games so much they are a part of her life. she enjoys life in a cycle of eating, sleeping, and gaming. She is a sore loser who gets angry and cries, even jokingly strangling her opponent when she loses a match. The Tachikawa Unit strategy room is filled with a large number of new and old game consoles she brought in, which the whole squad seems to play. Additionally, a small room in the strategy room serves as her nap room for all-night gaming sessions. She is well-endowed; in Volume 13 of the manga, her chest area was even adjusted with screentone. She attends a regular high school, but her academic grades are mediocre, and she, along with Toma, is looked after by their classmate Yuka Kon. In the BBF (Border Briefing File) grade charts, she is the 3rd worst among the girls, after Nire and Osano. Despite being a bit of a "hopeless girl," she reached A-Rank #1 alongside Tachikawa, proving that academic grades aren't everything. According to the BBF parameters, her equipment operation, information analysis, and parallel processing are top-tier among operators, and her total stats are #1. Perhaps because of her gaming hobby, her equipment operation is a 10, tied with Usami for the highest. Incidentally, her Trion capacity is 1, but she and Usami are the only two characters with a value that low. According to Tachikawa, the crescent moon in the background of the Tachikawa Unit emblem represents her. She does her job properly, efficiently preparing maps for Izumi during the fight against Ranbanein and delivering the latest info to Tachikawa, who cares about the New Model kill rankings. During the B-Rank Rank Wars Round 6, she formed the "18-Year-Old Idiot Trio" with Toma and Zoe for commentary, showing surprising intelligence by knowing what inverse proportion is. Her mother is from Hokkaido, and she joined Border about three years ago through out-of-prefecture scouting. Her mother's family sends Ishikari Nabe sets, sea urchin, crab, and salmon roe, which the whole squad eats together. The mysterious crab clock in the strategy room might also be a gift from her family.