Kei Tachikawa/Abilities

Being the No. 1 Attacker and solo combatant, Tachikawa is one of the strongest agents currently in Border. This is shown when he effortlessly cut an Ilgar in self-destruct mode apart using Double Senkū which impressed Yūma, while Kitora, a seasoned A-rank Ace struggled to take down a self-destructing Ilgar. More proof of his strength is that he was the agent who had killed the most Rabbits on his own (eleven) despite Replica predicting that a lone A-rank agent would have trouble with just one. Another impressive achievement is his ability to fight on equal ground with a Black Trigger-wielding-Jin by himself for most of their fight, before losing to the latter's Side Effect. His dual-wielding Kogetsu style was passed down to him from Shinoda. Usami stated that Tachikawa is the superior swordsman between Jin and him, although she also noted that their matches have been tied since the latter began using Scorpion. Further proof of his skill is offered by his solo matches against Hyuse. Although the latter had been even with the No. 6 Attacker Ikoma, Tachikawa single-handedly defeated him five times out of six, scoring the last win by casually cutting Hyuse twice without his opponent being able to react. After their match, Hyuse commented that a swordsman of Tachikawa's skill is not common, even in Aftokrator.

While he prefers to fight head-on, he can also be analytical, as demonstrated during his commentary and when he defeated Gatlin with Konami's help. According to Jin, it is extremely unusual for Tachikawa to lose his composure in combat. By using Grasshopper to get close to opponents that Senkū alone cannot reach, his range matches that of a Shooter despite him being an Attacker.