As the zanpakuto of the Captain Commander of Soul Society, Ryujin Jakka boasts of a power that extends beyond the laws of physics. It is the first of its kind to be ever created, and from a purely offensive perspective, it remains unmatched. Interestingly, its wielder, Genryusai Yamamoto, keeps it hidden away in the form of a staff, but it is deadly even in this form.
The Bleach anime storyline explains the various aspects of its shikai, including certain abilities such as Taimatsu (a blazing inferno), Jokaku Enjo (a fiery prison), and Ennetsu Jigoku (terrifying towers of flame encircling the opponent). But Ryujin Jakka has received a lot more attention in the manga-specific Thousand Year Blood War arc, mostly for the revelation of its bankai.
10 Its Shikai Is Powerful
This is a fact that bears repeating, because the old man apparently has a lot more tricks up his sleeve than the ones already televised. For instance, when the Wandenreich Quincy enter Seireitei, Driscoll Berci, the man who had recently murdered his beloved Vice Captain Sasakibe, threatens him with the former's stolen bankai.
The attack doesn't just fail, it transports Yama-jii to the past where he indulges in some pleasant nostalgia for a short time. Immediately after, he mocks Berci for failing to use Koko Gonryo Riku properly, and promptly literally dissolves the flesh from his face.
9 Helps Yamamoto... Fly?
As Shuhei Hisagi runs to his aid, Yamamoto asks him to stay strong and be proud of his courage, claiming that it will be himself who will end the invaders single-handedly.
As he makes this announcement, he propels himself from the ground and flies at hypersonic speed towards Yhwach, all the while covered in a sheath of incandescent fire. This is interesting, because none of the other Shinigami are capable of flight within the bounds of Soul Society, as they are in the real world.
8 One Hit For Three Opponents
The old man threatens his ancient enemy with a painful death, but is surprised by an attack coming from above. Three extremely powerful Sternritter— Nanana Nahjakoop, As Nodt, and Bazz-B— arrogantly try to strike him down, but their failure is as monumental as their audacity.
The actual fight is not shown, but it takes less than a few seconds, concluding in a gargantuan plume of flame that leaves each of them burned nearly beyond recognition. They survive, although barely and with immense difficulty.
7 Its Bankai Is Zanka No Tachi
Aware that nothing less than his bankai is capable of affecting a being like Yhwach (given that they had fought a millennium ago), Yamamoto triggers Zanka no Tachi. All of his fire seemingly disappears, prompting the villain to wonder if the Captain Commander even intends to fight him.
However, the influence of this splendid bankai quickly begins to show itself across Seireitei: Kyoraku's lower lip receives a minor bruise, Ukitake's throat becomes parched, and, most impressively, Hitsugaya's Daiguren Hyorinmaru— at the time in the possession of Cang Du— turns into a useless puddle of water.
6 East: Kyokujitsujin
Zanka no Tachi has four modes, named after each cardinal direction. East, or Kyokujitsujin, gathers every possible bit of inferno generated by Yama and sleekly aligns it on the edge of the zanpakuto.
This is radically different from his shikai, but far more dangerous because the blade can instantly vaporize anything it comes into contact with. There is no defense possible against this technique, which is why Yhwach asserts that all he needs to do to not die is kill the old man without going near the sword.
5 West: Zanjitsu Gokui
Yhwach's tactic is a gross misstep, because he doesn't consider the possibility that a West would also exist— in this case, known as Zanjitsu Gokui. It's not entirely his fault, though, because it only becomes visible when the Captain Commander chooses it to be so.
This ability makes a solid case for Yamamoto's practical invulnerability, since Zanjitsu Gokui is a cloak of heat-based reiatsu that somehow burns at the temperature in the core of the sun, 15 million °C (or 27 million °F). Yhwach learns this the hard way, by finding out that the top of his blade has mysteriously vanished.
4 South: Kaka Jumanokushi Daisojin
The most terrifying aspect of Zanka no Tachi, at least psychologically, is Kaka Jumanokushi Daisojin. When Yama-ji pierces the earth with his bankai, he chants a short mantra invoking everyone who had died by his hand to return to the living world (as zombies).
These creatures might be half-rotten but there are simply too many of them, and they appear with the weapons that were part of their original characters. Yhwach's Quincy shield, the Kirchenlied: Sankt Zwinger is no match for the explosive power of this approach, and is immediately shattered.
3 North: Tenchi Kaijin
The last move available to Yamamamoto Genryusai, in his bankai form, is North: Tenchi Kaijin. The name of this technique alone is more intimidating than most other Shinigamis actual zanpakuto— it reads, to translate it loosely, "the reduction of both heaven and earth into ash."
It is visible as a lightspeed flash of pure white, and effortlessly carves a massive segment of the villain's abdomen, resulting in his death. The exact mechanism behind Tenchi Kaijin is unknown, but given its placement, it can be assumed that it is far more destructive than its predecessors.
2 Zanka No Tachi Is Stolen
Unfortunately for the Captain Commander, he comes to realize that the man he has been fighting this whole time is not Yhwach at all; in fact, it turns out to be a copycat Sternritter, Royd Lloyd.
The real antagonist then manifests himself behind Yama, inciting him to reactivate Zanka no Tachi. This time, however, Yhwach successfully robs him of his bankai with a Quincy Medallion, snidely stating that the old man's time is finally nigh.
1 It Is Shattered To Pieces
Yhwach kills Yamamoto on the spot, slicing him apart diagonally from torso to hip. The old man's upper half falls to the ground, while his legs continue in their standing position. When the villain attempts to leave the scene, the "corpse" grabs him by the cloak, resulting in his wrist getting hacked off.
Yhwach then admonishes the Captain Commander for not evolving with the times, and pretty much atomizes his body with a series of consecutive reishi bombs. Only Ryujin Jakka is retrieved by the Gotei 13, and nothing but shards of the once overwhelming zanpakuto.