The following contains spoilers for several episodes of BLEACH: Thousand-Year Blood War Part 2, available for streaming on Hulu and Disney+; as well as heavy spoilers for the Can't Fear Your Own World novel series by Ryohgo Narita, overseen by Tite Kubo.

In the first four episodes of the second cours of BLEACH: Thousand-Year Blood War, series protagonist Ichigo Kurosaki is barely seen as he embarks on a kind of training with the Royal Guard in order to gain immense power. Captain-Commander Shunsui Kyōraku made a trip to the World of the Living to personally deliver Soul Tickets to Ichigo's friends, due to the possibility that Ichigo will no longer be able to return when the war is over. Kyōraku doesn't fully explain why, but in the post-credits scenes, Royal Guard member Ichibe Hyōsube eerily narrates the path upon which Ichigo has embarked.

What these moments are building up from is perhaps one of the most heinous incidents in history – the very thing that inspired Sōsuke Aizen to raise his sword against not only Soul Society, but against the very constitution of the BLEACH universe. The "Irazusando" post-credits scenes are a glimpse into the preparation of Ichigo Kurosaki to become a vessel for the Soul King.

RELATED: Bleach: Who is the Soul King?

Sacred Training

The first episode of the second cours of BLEACH: Thousand-Year Blood War, Ichigo has just recently had his Zanpakuto reforged as per the events of episode 13, "The Blade is Me". He embarks on training with Ichibe Hyōsube, who tells him that the Quincies should be returning very soon. Hyōsube tells him that the only way to beat Yhwach is for Ichigo to surpass the limitations of a Shinigami; an important clue regarding the very nature of his training. Armed with only a wooden sword, Ichigo is placed in a mysterious alley with a stone path stretching out before him. This strange space is a sacred area that one can only enter with permission from the Soul King. On either side are several dangling white threads with a zig-zag shape. Threads or ropes have come up as a motif several times in this second cours of BLEACH: Thousand-Year Blood War – in Ichigo's training, in Rukia and Renji's training and even with Komamura's Bankai. The task is simple: reach the shrine-gate on the other side.

Irazusando

"It begins, but does not end. Names wither in the silence. In an abyss of rolling clouds, raindrops fill an empty vessel. Those who are unfit to become a vessel succumb to its weight as it turns to stone. It breaks apart and turns to gravel. Pounding rain reduces it to dust. For such a vessel, there is no way out. But if one does not enter, there is no path. Those who are about to perish call it... Irazusando".

Irazusando has two operative parts: "Irazu", meaning "no entry", and "sando", meaning a path approaching a shrine. Together, this would be "no entry to the path approaching the shrine". Ichigo's approach appears endless as the goal right ahead of him feels like it stretches continuously despite his approach. Ichigo continues, and is hit by a flurry of visions too fast to see clearly. If one slows them down, they can just barely make out the visage of someone in a watery region turning what looks like a key in one of four whirlpool-like shapes in the water.

Various arrows are seen in the water acting just like the aforementioned key, and the silhouette of a person is seen: whole at first, before its right and left arms, followed by its legs are torn off and thrown into the water, while its torso floats lifelessly. Ichigo's reiatsu fluctuates a little before the visions flash again, this time more clearly than the last, and more information is relayed as Ichigo sees what has become of the silhouette figure. Finally, Ichigo's bewildered eyes become the focus as 4 additional irises appear in his eye, and he feels a certain heaviness. Hyōsube continues his trance-like narration of Ichigo's situation. "The weight you feel is what you're trying to protect. Everything you see are everlasting memories and revelations – in other words, the power of the King".

Colourful Thread

The moment Hyōsube identifies the source of the heaviness as the Soul King's power, more visions flood Ichigo's mind. This time; however, the noticeable four-pointed star shape seen in the Royal Guard's insignia now frames these visions as Ichigo continues – it's like he's seeing the visions through different eyes. It becomes evident that these are memories flooding into Ichigo's mind. The next frames have the threads hanging in the background fill with shimmering streaks of light of various colours. Ichigo stands directly in front of one as reishi strands of various colours begins to enter his body, and the streaks begin to weave around each other like thread. Four major streams of different colours of iridescent light enter Ichigo, and he screams as the incredible power flows into him.

The entire picture goes black and white as Ichigo struggles to contain it, and the four additional irises in his eyes return once more. His body is shown to be bulging and contorting in response as his silhouette is deformed. The light intensifies in brightness as Ichigo raises his wooden sword turns a radiant white, illuminating the scene. Those giant white threads on the side now appear to be pillars – like those one would find in the Soul King's palace. Once the burst of energy subsides, Ichigo drags along and finally reaches his destination – Royal Guard member Shutara Senjumaru, otherwise known as the Great Weave Guard, whose chambers are filled with various pieces of beautiful cloth.

Can't Fear Your Own World

All the way back in the first arc of BLEACH, Ichigo learned how to track reiatsu from Uryū, an action which materializes the reiatsu into threads which are normally white. A red one would indicate a Shinigami's reiatsu. The relevance of this visualization continues into this arc, with the last of Ichigo's post-credit scenes coming in the 17th overall episode, "Heart of Wolf". In the Can't Fear Your Own World novel trilogy written by Ryohgo Narita, it is explained that the Soul King was a composite entity who came into existence during a time of primordial chaos. A conspiracy by the ancestors of the Five Great Noble Clans of what became Soul Society led to the apparent murder and dismemberment of the Soul King, with his body being used as a linchpin for the BLEACH universe. The five Royal Guard members correlate to the Soul King's arms, legs and torso; while the five-points on the Quincy Starcross may be another nod at these five major pieces.

His body parts and organs gained sentience during their separation, but the most important were his arms, which governed the very concepts of stillness and evolution, with the former being hosted in the body of a certain Captain, and the latter, a certain Quincy. In the novels, it is revealed that fragments of the Soul King have worked their way into various souls over time. Aizen knew about the primordial murder of the Soul King and strove to transcend boundaries as an existence through creation and use of a Hōgyoku; however, the reason he needed to use one was because an entity like the Soul King – one that is Hollow, Quincy, Shinigami and Human (Fullbringer) – cannot maintain a stable existence due to the conflicting forms of life that make up its composition. In the anime, only one person alive is known to possess the necessary composition to become the next Soul King: the Substitute Shinigami, Ichigo Kurosaki. This would have him become the sacrifice "necessary" to continue the current structure of the world, and most probably, physically incapable of leaving Soul Society.

MORE: Bleach: 8 Best Fights In Thousand Year Blood War Anime, Ranked