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 apart in one swing while Kitora struggled to even scratch the Ilgar. More proof of his strength is that he was the agent that had killed the most Rabbits on his own (eleven) despite Replica stating that an A-rank agent would have trouble with one Rabbit if they were on their own. Another impressive achievement is his ability to fight on equal ground with a 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 match have been ties 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.06 Attacker Ikoma, Tachikawa single-handedly defeated him five times out of six, scoring the last win by casually cutting Hyuse twice without him being able to react. After their match, Hyuse commented that a swordsman of Tachikawa's skill is not common even in Aftokrator. While in battle he prefers to fight head-on, he can also be analytical, as demonstrated during his commentary and when he defeated Gatlin with Kirie'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.
Tachikawa is a master at using Kogetsu, and is generally regarded as the best swordsman in Border after his teacher. With it, he rose to the rank of No. 1 Solo Fighter, repeatedly besting Jin despite the latter's Side Effect. He can fight with either one or two, switching to the dual-wielding style taught to him by Shinoda. His single-wielding style alone caused him to win 6 times out of 5 against Hyuse, and cause the latter to admit that swordsmen of that level are uncommon even in Aftokrator.
Tachikawa uses Senkū to increase the range of Kogetsu in an instant, performing a wide and deadly attack. He was able to cut down three damaged Rabbits with one slash each, the latter two within the same activation. However, he is allegedly less skilled than Tatsuhito Ikoma with this Trigger.
Double Senkū Kogetsu (ダブル旋空弧月,Daburu Senkū Kogetsu?):[BBF Q167] Tachikawa can activate Senkū through both the main and the sub while wielding two Kogetsu. It is very likely he used this technique to effortlessly cut down an Ilgar, whose already durable armor was enhanced as it was ready to self-destruct.