Roronoa Zoro's Purgatory Onigiri is one of the most powerful techniques in his already famous arsenal of the Three Sword Style. It's basically an Oni Giri, his patented slitting attack technique done with three swords at one time by crossing the two on the chest and holding one in the mouth. This makes the Purgatory Onigiri take this already strong technique to a whole new level of power, outlining Zoro's growth and real mastery of ways of the sword.
The technique finally made its anime debut in episode 934 of the anime adaptation of One Piece, for the Wano Country arc. This time, Zoro had to improvise much as he combined Hitokiri's kama, which is a type of sickle, with his Soper Three Sword Style in performing Purgatory Onigiri. This adjustment says much about how Zoro can adapt right away but still maintain his style, even with the most unlikely weapons, showing both idiocy and brightness in adaptation during a fight.
Zoro's technique names include "Onigiri," which is a dual entendre. Literally, it means "demon slash" or "ogre cutter," but it is also one of the names of very popular Japanese rice ball snacks. This is typical of Eiichiro Oda's creativeness in naming things within One Piece; many of those names are food-related.
Purgatory Onigiri is, according to the anime, quite majestic. It`s actually used along with Zoro's fast and strong movements and a certain pattern in which the slash goes. Fans praised the quality of the animation for this technique in particular, with some versions being remastered in 4K and 60 frames per second to be super fluent and impactful.
Purgatory Onigiri is an indication of how substantially powerful Zoro has become, compared to before the time skip, in the One Piece storyline. He applies this technique to high-caliber targets, so among his attacks, this would definitely be one of the more powerful. This prefix "Purgatory" suggests a level of intensity or sufferance that the target is to undergo upon this attack, much like how Buddhist-inspired themes are attached to most of Zoro's techniques.
This usually has Purgatory Onigiri with Zoro directly and powerfully charging towards the enemy, then delivering the slashing attack. The added speed therefore adds to the power of the technique and makes it highly useful for covering large distances between him and his target in a fight. It is, however, important to note that sometimes the anime takes liberties with the exact positioning of characters for dramatic effect, which some fans pointed out.
Zoro continued to hone and increase the strength of his techniques over time. Evidence in much later episodes, for example, episode 1062, shows that Zoro uses an even more powerful version of this attack known as "King of Hell: Purgatory Onigiri." This alternate version of the technique seems to indicate that Zoro himself is developing further and that challenges he faces in the New World are becoming increasingly more difficult.
Purgatory Onigiri is, without a doubt, one of the most famous techniques often used in promotional materials and around the One Piece community. Its usage in pivotal fights, such as in the Wano Country Arc, forever connected it to being one of Zoro's many powerful moves.