If someone already covered this somewhere, sorry. I don't read spoilers and didn't see it elsewhere. If a mod wants to combine it please do so but since Zoro is a BMF he deserves this.
Rashoumon 羅生門
An odd choice. Both Kanji and kana are exactly the same as the title of the novel and classic Akira Kurosawa film. He usually packs a few meanings in there. The kanji may be literally read as:
The Life-Catching Net Gate. A 'ra' is literally a net for catching birds or also "guaze" and is a real gate in Kyoto.
Gyuuki Yuuzume 牛魂 勇爪
MUCH COOLER SOUNDING AND A MUCH COOLER BACKSTORY THAN RASHOUMON but ultimately a much less sweet move in my opinion (like anything can beat a 'drawing technique'). A Gyuuki is a Cow Demon but distinctly Japanese, as opposed to the Buddhist Cow Demon known as a 牛頭 or Gozu. This nasty ass MOFO lives in the sea (and by no coincidence the gang is at sea) and comes from Ehime Prefecture on Shikoku (YAAAAY! I LOVE EHIME). This demon will eat up anyone that sees it and bears some nasty long claws. It should also be noted, this demon is called 'Ushi Oni' not Gyuuki so maybe something else is in there. Hence the attack:
Cow Demon's Brave Claws
Why brave for what is traditionally a nasty demon? BECAUSE THAT'S WHAT ZORO IS!!! HE CUT A FRIGGING TRAIN IN HALF!!!!
The fictional demon was supposedly mentioned in Sei Shonagon's classic work The Pillow Book.
Want to see a Cow Demon? Be my guest:
http://www10.ocn.ne.jp/~hiko/ushioni.htm
Ugly bastard.