Seizo is a tall, muscular man with brownish red hair. He has long sideburns and a long ponytail hanging down his back kept in place with a red tie. His face has some slight stubble growing above his lip and on his chin. Seizo wears a standard shihakusho but with a few small variations. He keeps the sleeves rolled up onto his shoulders at all times. He also wears white cloths around his back and arms that are tied together in front. Seizo has his wrists wrapped in bandages.
In his younger days, his hair was a more vibrant dark red. His ponytail was shorter and he did not have any stubble on his face.
Personality
Seizo is a very kind and helpful man. He always does what he is told and has no problems with doing the 11th Division's more menial tasks. He always offers help or assistance, giving Ichigo Kurosaki some ointment for his bruised forehead and later offering Ichigo advice on how to beat Renji in a sparring match. Ichigo noted that he is very mild-mannered, unlike the rest of his Division. Through years of work, he has become extremely efficient in doing the chores of the 11th Division, beating Ichigo in a race of washing clothes, hanging laundry and other tasks, with ease. He is an extremely noble fighter, never wanting to use any kind of trick to gain the upper hand. When he used to fight Ikkaku Madarame, he never resorted to any ploy even after losing constantly. He does not back down, no matter how impossible the challenge is. He places the safety of other above his own, pushing Ikkaku out of the way of a Hollow and taking the attack himself.
History
Seizo joined the 11th Division around the same time as Ikkaku. He was a promising Shinigami whose sword skills were a sight to behold. He often sparred with Ikkaku but lost repeatedly due to not wanting to use any kind of trick. Even though he kept losing, he would not give up.
Seizo is drained of his power.
One night, Ikkaku and Seizo were a part of a team tracking down a Hollow. Seizo volunteered to go on ahead but Ikkaku protested, saying that he had lost their matches too many times. Seizo refuted this, saying that they were simply draws but hesitated for a moment once the Hollow appears. Ikkaku ran up ahead and struck the Hollow. When the Hollow went to attack Ikkaku, Seizo pushed him out of the way and took the attack himself, leaving him drained of his spiritual power.
Source: bleach.wikia.com