Baishin

Baishin (白沙, Baishin?) was a Shinigami who appeared in the OVA The Sealed Sword Frenzy.

Synopsis
He was once a member of the Gotei 13, but went insane killing 63 seated officers before escaping to the human world. Six of the thirteen captains chased him and it took the sacrifice of two of them to seal him away. He eventually broke free the statue where he was sealed, killing in the process everyone in the area. 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 not effect and gets stabbed with a dagger. Ichigo transforms into a Shinigami and begins to fights Baishin, who calls him self Blade. As Ichigo attacks, Baishin grabs him and takes some of Ichigo’s spirit power. Renji and Rukia attack but are too weak to hurt him then, but in that moment Tōshirō Hitsugaya shows up and however scares away Baishin. But before Baishin leaves he unleashes a bunch of Hollows then disappears. At the site where he was once sealed, Ichigo then releases his spirit power to a track Baishin. Baishin once again fought 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 was eventually killed by Ichigo using his own final release. 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 thean zanpakutō he once become one with.