Kodachi Nitō Ryū (小太刀二刀流, "Double Kodachi style"): Is the name of the fighting technique used by Shinomori Aoshi. During his first appearance in the Rurouni Kenshin series, Aoshi used only one kodachi, which he mainly used for defense while pummeling his opponents with his hand-fighting prowess (he was extremely skilled in Kenpo). However, during Kenshin's fight against Aoshi, the secret and weaknesses behind Aoshi's technique are unveiled. At close range, an opponent with a longer sword has a blind spot due to them having a longer reach than the shorter, light sword Kodachi. Aoshi would then trap the sword with his Kodachi using the blind spot, and beat his opponent with punches and kicks. However, after much struggle, Kenshin figured out that by holding his sword by the dull edge, the difference in reach would vanish, so the blind spot was naturally eliminated. Aoshi then acknowledged Kenshin's skill and moved in for his devastating Kaiten Kenbu, which he would appear to kill Kenshin with at first glance.
The latter however survived by using his scabbard as a buffer to halve the strength of the three deadly slashes, and when he attempted the attack again, Kenshin mustered the last of his power to catch Aoshi's sword the only instant he was vulnerable, defeating him by striking his throat with the hilt of his own Kodachi, rendering him unconscious for a short moment.It is only at the beginning of the Kyoto saga when Aoshi begins to utilize his twin kodachi fighting style. By doing this, he strengthened his offense considerably, and his defense now has no such exploitable flaws due to there being an extra sword to fend counterattacks with. Due to his increased speed and strength from the training he did beforehand, this now made him one of Kenshin's strongest foes yet.
When Gein faces Aoshi he is constantly surprised by the latter's techniques and notes that his skills are much higher than they were when he fought against Shishio Makoto during the Kyoto arc. This is most likely due to Aoshi having cleared his mind and soul through meditation and having found a true purpose to work for, i.e. eradicating the evil practitioners of the dark arts (Gehou), which is exactly what he does when he kills Gein.
Onmyō Kōsa: (Shadow-Light Cross) Aoshi blocks an enemies striking weapon with one kodachi, then strikes it with the second kodachi, thrusting the first one through. It can slice even the toughest of shields, including steel tonfa that are supposed to repel any sword attack.
Jissen Kenbu: (Actual-Battle Sword-Dance) Combo attack using "Ryūsui no Ugoki" to flow around the enemy, confusing them with a constant change in speed. Aoshi will then strike from various points, slashing them with his kodachi, then ending it with "Kaiten Kenbu". Before deciding to use a two kodachi style of fighting, this was Aoshi's final attack. Though he is nearly impossible to hit during the Jissen Kenbu, he is vulnerable for an instant when he switches from a defensive to an offensive stance, a weakness exploited by Kenshin, and later Shishio.
Kaiten Kenbu: ("Spiral Sword Dance" or "The Dance Of The Wheeling Sword") Aoshi claims to have used this attack to defeat "all who have intruded upon Edo castle". It involves Aoshi rapidly spinning around three times, while holding the kodachi backhand, to slash the opponent thrice in an instant. Aoshi usually uses this attack after disorienting the opponent with Ryūsui no Ugoki. Only by using his scabbard as a buffer was Kenshin able to survive this attack.
Kaiten Kenbu Rokuren: ("Spinning-Heavenly Sword-Dance Six-Series" or "The Dance Of The Wheeling Sword Six Successions") This attack is Aoshi's ōugi. The attack involves Aoshi gripping his kodachi backhand, then slashing the opponent six times in rapid succession, from both sides (it relies on confusing the opponent on the direction from which each subsequent strike is going to come). It's basically Kaiten Kenbu but done with two kodachi, the key difference being that the unpredictability of where it strikes first puts the opponent at a disadvantage. Only Kenshin and Shishio, Aoshi's strongest enemies, have beaten this attack. However, it should be noted that Aoshi was severely weakened by Kenshin's ougi first.
Onmyō Hasshi: (Dusk to Dawn Strike) Aoshi throws both kodachi at the opponent, hitting the end of the first one with the second one for an extra boost. The second kodachi is hidden directly behind the first, so the opponent would only see one kodachi heading for them in their line of sight. If such switf opponents as Kenshin are able to avoid both the swords, Aoshi usually uses this opening to kick them while they are vulnerable.
Gokō Jūji: (Yin-Yang Cross) Aoshi crosses the two kodachi and moves them outwards in a scissor-like cut, usually to kill the enemy by slicing their caratoid artery.
Ryūsui no Ugoki: (Flowing-Water Movement) This is moving technique where Aoshi moves around silently, rapidly alternating between fast and slow movements and confusing the opponent due to the fluid motion & continuously changing speed. It can be beaten by watching for the moment the user attempts to strike.
Even though Aoshi's skills rarely fail him in the midst of combat, he's still able to adjust and adapt to the direst of situations, even to the point that he hides himself in a recently dug grave to escape Gein's burning end.
- The Kodachi Nitō Ryū was apparently self-taught, but at least based slightly on observing the former Okashira's battles, as it was originally his forte.