Baishin

was a Shinigami who appeared in the OVA The Sealed Sword Frenzy.

Appearance
Baishin's appearance is that of a middle aged man with a beard and blades growing out of his shoulders. He can transform parts of his arms in to blades that he can then lunch to his enemies. He also wears a samurai-like armor over his shinigami hakama.

History
400 years prior to the main Bleach storyline Baishin found a way to merge himself with his Zanpakutō, as a result he went on a rampage. He is responsible for the death of 63 seated officers of which some were lieutenants, and proceeded to escape to the real world. A total of six Captains were sent to capture him, two of them which lost their lives while the remainder were able to imprison him.

Synopsis
Baishin eventually broke free the statue where he was sealed, killing everyone in the area while doing so. He hunted down those with powerful spiritual energy, and Baishin found it in Ichigo. He confronts Renji Abarai and Ichigo Kurosaki. Renji shoots him but with it has no effect and gets stabbed with a blade. Ichigo transforms into a Shinigami and begins to fights Baishin, who calls himself a blade. As Ichigo attacks, Baishin grabs him and takes some of Ichigo’s Spiritual Energy. Renji and Rukia attack but are too weak to hurt him then. Just at that moment, Tōshirō Hitsugaya shows up and scares away Baishin. Before Baishin leaves, he unleashes a bunch of Hollows then disappears. Traced to the site where he was once sealed, Ichigo releases his spirit power to a track down Baishin. Baishin once again fights Ichigo, this time with Rukia and Renji at Ichigo's side. However, by sucking out Ichigo's spiritual power, Baishin was able to perform his final release. Baishin summons his bankai which transforms his skin into metal, becoming a living being of swords. He is eventually killed by Ichigo using his own bankai. After Baishin dies Ichigo reveals that Baishin had merged with his Zanpakutō. Yoruichi thinks that Baishin tried to use Ichigo's spirit power to return back himself to normal, separating his body, and his Zanpakutō, even if he perished. The only thing left of Baishin is the Zanpakutō he once merged with.

Powers and Abilities
Having merged with his Zanpakutō, Baishin is capable of transforming his arms into blades. He can then fire them at his opponents, allowing him to fight both at close combat and at a distance. Baishin seems to have the ability to call upon Hollows but it may just be that they are attracted to him because of his spiritual energy.
 * Shikai: The name and release command of his Zanpakutō are unknown, due to the fact that when he is first introduced he has already merged with it.
 * Bankai: During the battle with Ichigo after absorbing a large amount of the former's energy he is able to released his bankai. While it is unknown weather this is his first time or if he just needed the power boost that Ichigo provided via his own power has been left unclear.