Ōetsu Nimaiya

is a member of the Royal Guard, holding the title.

Appearance
Ōetsu is a dark-skinned man with thick, black hair that is shaven and dyed green on the sides of his head. He wears a variation of the Shinigami shihakushō, featuring instead a green undergarment, and a shortened hakama that exposes his lower legs. Worn over this is a white, sleeveless puffer jacket that bears the Royal Guard emblem on its back, as well as the alternating circle and diamond pattern of a captain's haori along the bottom. His attire is completed by gold-framed sunglasses with blue lenses, and a pair of green slippers that are gold trimmed and have a shoe-like appearance.

Personality
According to Kirio Hikifune, he's an unpredictable man. Ōetsu is a quite lively and energetic individual, being prone to grandiose entrances and greetings. He has a tendency of going overboard, as he portrays a certain image as to take away from the fact that he lives in a humble state.

History
Ōetsu is credited with having created the Zanpakutō, something that even the Soul King recognized as a significant contribution to Soul Society, hence his promotion to the Royal Guard.

The Thousand-Year Blood War arc
After the death of Genryūsai Shigekuni Yamamoto, he arrives in Soul Society with the other members of the Royal Guard, where they are greeted by the surviving Gotei 13 captains and Ichigo Kurosaki. He remains silent throughout the encounter and they return to the Soul King Palace with Ichigo and the injured Byakuya Kuchiki, Renji Abarai and Rukia Kuchiki.

Ōetsu is informed by Mera that Ichigo and Renji Abarai have arrived at his domain and goes to greet them. Ōetsu identifies himself to them as the number one Zanpakutō creator and brings them to a building where they are welcomed by a number of women. He formally introduces himself, forcing them to perform an elaborate formal greeting. Mera interrupts and has the group follow her to a hut on the edge of a precipice. Ichigo and Renji step inside and Ōetsu tells them that he is the only Shinigami there and that the other people are actually Zanpakutō. He notes their inability to discern the difference and states that they have no love for Zanpakutō which is why they cannot tell the difference and then shatters their Zanpakutō, saying that a Zanpakutō that is not loved breaks easily. As they notice beings around them, Ōetsu states that the wrath of the Zanpakutō is around them, and that if they can get out alive, then he will reforge their blades.

After Ichigo and Renji begin their challenge, they begin seeing creatures spurring forth from the darkness. Ōetsu tells them not to be scared as they know them well. He states that the creatures are Asauchi. Ōetsu explains that when a Shinigami joins the Gotei 13, they are given a nameless Zanpakutō which they carry around at all times, even sleeping and eating with them, which imprints the essence of their soul on the Asauchi, creating their own Zanpakutō. He then states that he forges every one of the Asauchi. Ichigo asks why they are being attacked by the Asauchi and Ōetsu says that they are angry with Ichigo and Renji because of the way they treat their Zanpakutō. He says the way they treat their swords is all wrong and that is what the Asauchi think. He then poses a challenge, the Shinigami or the Zanpakutō, which will come out on top?

After about 3 days and nights Ōetsu stops the fight between Ichigo, Renji and the Asauchi. Ōetsu congratulates Renji on his skills and tells him he passes with flying colors, while he tells Ichigo that he has failed. Ichigo asks for more time but Ōetsu tells him that it's too late and it's over he is a complete failure. Ichigo pleads with him that he can keep going and he never stated there was a time limit. Ōetsu notes that while that might be true his patience does have a time limit and they have moved beyond whether or not he is capable, the fact is that the Asauchi have deemed him unworthy and therefore it's out of his hands. He further notes that if nothing else the last few days have shown him that Renji is a true Shinigami and Ichigo is in fact not one. He then assures Ichigo that the least he can do is send him home. Ōetsu then asks Mera to show Ichigo the door, he then tells Ichigo to never show his face in Soul Society as it's only a place for Shinigami and not a Human without a Zanpakutō. Ichigo asks him if he thinks he can just make him leave that easy and asks what will happen to Zangetsu if he leaves. Ōetsu tells him it doesn't really matter as either way it's not getting fixed. An enraged Ichigo lunges at Ōetsu. He restrains him and opens a portal that transports him back to Karakura Town, wishing him a pleasant trip. As the portal closes Ōetsu notes to himself that Ichigo needs to step up his game, as the Asauchi deemed him unworthy meaning Ichigo has been able to hold his own this entire time without the Asauchi's aid. Such a thing has great ramifications and therefore it's time for Ichigo to start from the ground up; he has to crawl before he can walk, even if that means never coming back again.

Ōetsu comments to Renji that he did not protest about him sending Ichigo away. He explains that he knows why, as the creator of the Zanpakutō he knows the position of every Asauchi he has ever created, whether they are common soldiers or captains, one way or another a Shinigami needs an Asauchi in order to make a Zanpakutō. He further explains the nature of acquiring a Zanpakutō and that Ichigo having a Zanpakutō without an Asauchi confirmed he was not a Shinigami. He states to Renji that he knew the method he devised would not be passed by Ichigo and that Renji knew it as well, in fact the only one that didn't know was Ichigo himself. Ōetsu points out that Ichigo needs to find out where his soul lies.

The next day, Ōetsu sends Mera to bring Ichigo back to his palace. He tells him that Ichigo has one night to make the Asauchi accept him, otherwise the time he spent will be wasted. However, he notices that the Asauchi have already recognized Ichigo's talents. As Ichigo selects an Asauchi, Ōetsu decides to personally reforge his Zanpakutō. He then sets up a slide to lead deeper into his palace, and kicks Ichigo into it, sending him down head first with his Asauchi. He then says that he warned Ichigo about the dangers of going in head first after they reached the bottom. As Ichigo gets to his feet, Ōetsu tells Ichigo to look around at the area they have arrived at and tells him to prepare to say goodbye to his current Zanpakutō, Zangetsu.

Ōetsu summons his bodyguards to prepare the forge for him. As he begins forging Ichigo's new Zanpakutō, he states that he wants to see the flame. He then explains the reason why Ichigo was shocked when he sees the form that the Asauchi took upon contact, revealing that the Ichigo's Zanpakutō is actually his inner hollow. He tells Ichigo that White was a Hollow made from a Shinigami's soul created by Sōsuke Aizen and that its composition was similar to an Asauchi. He reveals to Ichigo that he has been tricked and that the being he thought was 'Zangetsu' is not his Zanpakutō Spirit but the manifestation of his latent Quincy powers. He furthers mentions that the beings appearance is that of Yhwach as he appeared 1000 years ago.

As Ōetsu finalizes the forging, Ichigo, having spoken with the Quincy side of Zangetsu, chooses to keep it, grabbing the heated blade. While surprised by this, Ōetsu realizes Ichigo pouring his own soul into the forging would be better. As Ichigo lifts the blade, a huge eruption occurs, vaporizing the entire sea around them to cool off the Zanpakutō. Watching in acknowledgment as Ichigo holds his now-twin blades of Zangetsu, Ōetsu asks him how they feel.

Inventions

 * Zanpakutō: Ōetsu is the one originally responsible for creating the Asauchi, that are base template for what will become a Shinigami's unique Zanpakutō.

Powers & Abilities
Master Swordsmith: Ōetsu is the creator of the Zanpakutō and therefore the foremost authority on its history, construction and capabilities. He has the greatest understanding of the Zanpakutō, and is also the only one who can reforge a broken Zanpakutō. He creates the strongest Zanpakutō, the Asauchi, as they can become anything.

Zanpakutō Sense: He knows the exact position of all the Zanpakutō that he has ever created, no matter how the wielder attained it or who the wielder is.

Great Spiritual Power: As a former captain of the Gotei 13, Ōetsu Nimaiya has a great amount of spiritual power.

Zanpakutō

 * Shikai: Not Yet Revealed
 * Bankai: Not Yet Revealed