Zaneizan

""Eat this, from my master! A sword technique created by Kenzaki Ryūsei― Secret Style Sword Technique, Zaneizan!!""

- Hayato using Zaneizan

Zaneizan is a secret technique in the Kenzaki Dōjō and created by Ryusei Kenzaki.

Description
""What I created is, the destruction by the application of natural vibration.""

- Ryusei explaining Zaneizan

In the middle of the Second Attack in Yamato when neither of their conventional weapons could wound savages and/or dent their steel-like shells. At that point, Hokuto Kenzaki, the older brother of Ryusei forged a katana by using the variable stone that the Yamato armed forces found from a piece of meteorite since neither brothers could get it to react to them.

Once Ryusei was soon chosen to wield the pitch-black sword that his brother forged, it failed to eliminate the savages and it caused nothing more than dents. Soon enough, he decided to create a special technique, which causes destruction by using natural vibrations.

In the initial strike, the first long sword, the user strikes their intended target causing vibrations from the resistance; then in the second strike, the second long sword, the user causes the same vibrations resonating with the "first long sword" and amplifies it more than three times causing a strike that is able to break apart the steel-like shells of savages without issues.

This sequence of sword strikes is normally done in an instant, making it seem as if it were all in a single simultaneous strike. Touka had later explained that despite their major differences, a similar technique could be created using their fists instead of a sword like normal.

Weaknesses
Despite the power of this technique, if it were to be used with a normal sword, then it would be shipped unable to endure it, but sword made using variable stones and/or Hundreds can endure it without breaking.

Zanizan Nishiki
Zaneizan Nishiki is another technique, where Ryusei performs a series of strikes drawing an X-shaped cut line before their intended target is pulverized but the destructive power of this technique is decreased a bit compared to normal.

Doryuusen
Doryuusen is a technique, which Touka created by using the same concept as the usual Zaneizan, where she strikes the ground resulting in a cloud of dust as a smokescreen.

Zanshouken
Zanshouken is a technique, which Rebecca Martin devised under the tutelage of Touka Kenzaki, which uses her fists to cause vibrations instead of a sword.

Trivia

 * The kanji for Zanizan was originally (斬影斬, lit. Murder Shadow).
 * Touka has created the most variations for the original Zanizan.