Saidō seems to be a bit lecherous, due to him commenting on how he had a clear view of a soul's panties in the Fake Karakura Arc[1], as well as making up (rather lewd) reasons for why Rukia decided to stay in the real world, the main reason being how she was looking for "pleasures of the flesh", however, he also seems to be quite level-headed and kind, as seen in his first appearance in the anime he was playing with some children in Rukongai.
edit Plot
Agent of the Shinigami arc
He was sent to find Rukia Kuchiki in Karakura Town. Two years Rukia's senior, he seems to be a low or mid-level Shinigami (supported by the fact he is never seen activating his Zanpakutō), and Rukia states that she has never seen him before, however he did seem to be somewhat important as seen when he first appeared in the series the Onmitsukidō member who had assigned him to bringing back Rukia had stated that he would not have tasked him with that mission had it not been serious. Not long after his arrival he found himself pressed into service assisting Rukia and Ichigo Kurosaki against the Hollow, Grand Fisher. After being wounded by Grand Fisher, he fell asleep. However, he witnesses the conclusion of the battle and sees Ichigo defeat Grand Fisher. After Ichigo loses consciousness, Saidō comments on Ichigo's potential and decides to leave Rukia alone.
Fake Karakura arc
He was seen much later in the series during the Fake Karakura Arc in Kagamino City. He is revealed to have recently been put in charge of the area and appears after a group of Hollows chasing the soul of a young girl are destroyed due to the sheer Reiatsu of the Shinigami and Espada. Eikichirō notes on the beginning of the battle but also wondering who will win.
edit Powers & Abilities
Saidō's rank as a Shinigami is unknown however due to his affiliation with the Onmitsukidō it could be naturally assumed the he is part of the 2nd Division whose duties are also tied to the Special Forces, as are the extent of his powers. He fought against Ichigo Kurosaki when he first became a substitute Shinigami and was easily able to keep the fight in his favor with Zanjutsu alone.[2] The full extent of his Shinigami powers are still unknown.
* Expert Swordsmanship Specialist: This was shown when he easily fought against Ichigo (before his training with Urahara) due to his long years worth of experience.
* Hand to Hand Combatant: Saidō showed respectable skill in unarmed combat during his brief fight against Ichigo. He would use powerful kicks whenever he found an opening.
* Keen Observer: As shown when he had first fought Ichigo, he is highly perceptive as he noted that at the time Ichigo was relying solely on brute strength to compensate for his lack of actual skill.
* High Strength: Despite when fighting Ichigo, his opponent had a much larger sword, Saidō was able to force back Ichigo with each scuffle, even able to launch him several feet with a simple shoulder charge.
* Flash Steps Practitioner: Even though he was never seen performing them, it can be assumed that due to his ties with the Onmitsukidō, it could mean that he is simply a member of the 2nd Division and thus proficient in Flash steps.
Zanpakutō
Saidō's Zanpakutō appeared to be a wakizashi with a black hilt and gray guard. Due to his brief appearances it is unknown if he is capable of performing Shikai or communicate with his Zanpakutō.
* Shikai: Unknown.
* Bankai: Not yet achieved.