One Piece's Roronoa Zoro is the swordsman of the Straw Hat Pirates and one of the strongest fighters in the entire series. Being the second-strongest member of the crew after Luffy, Zoro is often in the midst of some of the most incredible fights and with every clash, he gets closer to his goal of replacing Mihawk as the World's Strongest Swordsman.
Roronoa Zoro has gotten incredibly powerful ever since the death of Kuina, which pushed him further to keep his promise to her and in doing so, he's attained some incredible power-ups. Not only has Zoro received power-ups in the form of some great swords but he's also developed some others such as the rare Asura that he's busted out on more than a few occasions. While every fan knows that Asura's power is incredible, a lot about it remains a mystery to the fans.
What Is Zoro's Asura?
Just like the other members of the Straw Hat Pirates' Monster Trio, Roronoa Zoro played a massive role in One Piece's Enies Lobby arc to help rescue Nico Robin and save the day. Just as Luffy powered up by creating Gear Second and Gear Third to take down Lucci, and Sanji tapped into the hellish flames of Diable Jambe, Zoro tapped into the power of the demon spirit Asura. While very little is known about how and why Zoro could use this ability, there have been hints of Zoro having a demonic presence from the very beginning of the story. In Enies Lobby, fans saw this presence of his get even stronger and, at one point, Zoro's demonic aura manifested itself in physical form, surprising even his own allies.
In the fight against Kaku of the CP9, this demonic aura of his kept getting stronger and as the fight continued, it started to manifest further. Kaku felt that he got overwhelmed by his aura at one point and broke into cold sweat. Once again, the indication was quite clear that within Zoro lies a demonic aura that he can manifest in times of need. Whether this aura of his is related to his Haki or not remains to be seen, however, it is very much possible for that to be the case since Asura is a manifestation of his willpower.
Zoro finally tapped into Asura against Kaku and, by doing so, he could use the "Demon Aura Nine Sword Style." As the name suggests, this form allows Zoro to manifest two more heads and four more arms using his spirit, taking his overall sword count to nine. When used against Kaku, Zoro was able to power through his strongest Rankyaku with ease and defeat him in a single attack. He went on to use this technique once again during the Sabaody Archipelago arc where the Straw Hat Pirates faced a Pacifista. Unlike the last time, however, Zoro's usage of Asura wasn't enough to take the Pacifista down.
After the timeskip, Zoro was never pushed to a point where he felt like he needed to use the pinnacle of his abilities until he faced the Yonko of the Sea, Kaido on top of the rooftop of Onigashima. To protect his Captain, Zoro tapped into the power of the demonic form of Asura once again and clashed with Kaido. Surprisingly, Zoro managed to injure Kaido deeply by leaving a scar across his chest – a feat that only Kozuki Oden other than him has accomplished.
Zoro's Asura Techniques
Zoro's Asura is the very pinnacle of his ability as a swordsman. It allows him to increase his attack power by three times, by creating 6 more swords for him to use in combat. During Zoro's very first usage of the Asura Style against Kaku, he used a technique called the "Demon Aura Nine Sword Style: Asura Ichibugin," and this technique was quite incredible in itself. Unlike Zoro's other techniques, it didn't power through what was in its path. Instead, it turned it into mist and then followed up by landing quite a powerful blow on Kaku. This attack was so strong that Kaku was unable to continue fighting. However, he wasn't knocked out by Zoro's technique, showing that it still needed work.
Against the Pacifista on Sabaody Archipelago, Zoro used Asura: Makyusen, and this technique was quite similar to Ichibugin in how it saw him arrange his swords. Its application was completely different, however, as it saw him pierce the steel armor of the Pacifista with ease and even draw blood from him. Sadly, this technique wasn't powerful enough to completely defeat the Pacifista, however, it did play a significant role in bringing it down. After the two-year timeskip, Zoro's power had increased significantly, as did the potency of the Asura techniques. Against Kaido, Zoro used a technique called Ashura Bakkei: Mōja no Tawamure, and this technique is one of Zoro's very strongest to date. In application, it resembles Zoro's Makyusen quite a lot, however, it is much more powerful. Along with the power of the demon spirit of Asura, this technique also sees the application of high-level Armament Haki. At the same time, it also drew upon his Conqueror's Haki. Thanks to that, Zoro's power grew manifold when he fought Kaido and allowed him to scar the Yonko permanently.
Zoro still has quite a lot left up his sleeve, especially now that he has mastered Enma and gained a decent grasp over his Conqueror's Haki. In his upcoming fights, fans will likely see him utilize Asura to the fullest and maybe even take on someone close to the level of a Yonko.