Sanzo Fuji is the 5-year older brother of Rokusuke Fuji.
Like his brother, Sanzo is a good-looking and attractive man, although he is usually teased by his brother because of his early receeding hairline. He has a handsome face and black, short hair, and a tall stature; however, due to his seriousness, he appears older than his true age and is often mistaken as Fuji's father. He is most commonly seen in formal Japanese clothes, but he also wears normal T-shirt and dark pants when he goes to his university. Most of the times his eyes are close, giving him a composed appearance; although they are slightly open when he is angry. Iku Ashitaba noted that when Sanzo opened his eyes, the entire atmosphere around him changed and turned into some kind of murderous intent.
Sanzo is very serious in everything he does, and is an epitome of an ideal and perfect son. Unlike Fuji who is sometimes rude or disgrateful, Sanzo uses formal speech and is polite to anyone. His manners are usually graceful and refined; the only time when he loses control over his appearance was when he first saw Fuji's disease demon. Although he often fights with his brother, he actually cares a lot about him and is troubled by the fact that his brother rarely talks about himself at home. To those who have done something for him, he holds great gratitude towards them and never fails to express it whenever he has a chance. He is also somewhat stubborn and persistent, as commented by Fuji.
Sanzo is the eldest son of an extremely rich and traditional family which runs a high-class restaurant called Murasaki. Due to the strict upbringing he was given, Sanzo gives off a formal feeling in his manners and speech. He is very serious, and is willing to do anything suited for his family, as shown when he agreed to marry the person who was engaged to him rather than his girlfriend. Ever since his brother adopted the "I won't do anything troublesome" attitude, Sanzo has found it hard to be close to him like before. He is always troubled as to why Fuji has grown up that way, oblivious to the fact that he himself was partly to blame.
Sanzo was first introduced when Iku Ashitaba and Rentarou Mimasaka were trying to run away from the latter's mother in Parent's Day, being surrounded other mothers. Although Mimasaka noted that his face was creepy, he didn't relate Sanzo to Fuji until Ashitaba and he were asked about Fuji's whereabouts, upon which they mistook Sanzo for Fuji's father. The two then led Sanzo to the infirmary, where they met Itsuhito Hades wondering what he should do about Fuji and learned that Sanzo wasn't Fuji's father, but his older brother. Sanzo eventually found out that his brother usually skipped class and hid in the infirmary, and opened his eyes for the first time, giving him a dangerous aura. After apologizing to Hades-sensei about Fuji, he flipped the bed, only to find his brother hiding under it. Sanzo soon left, but not before scolding Fuji about his manners.
When Hades-sensei, Ashitaba and Mimasaka visited the Fuji mansion, Sanzo smacked his brother's head as he caught the latter trying to get his teacher and friends to go home before something bad happened. Sanzo then gave the visitors "boards", explaining that those would keep them alive in the household. He appeared again when Hades-sensei and the others noticed Fuji's being missing, and quickly accused his brother of being selfish, which he was corrected by the teacher. Together with them, he found the elevator leading to the "Garden of Laziness" created by Fuji's disease demon, and accidentally left his mouth hanging open due to shock. He brought a real sword with him when they all entered the garden. As they found Fuji sleeping in a pod, he immediately tried to break it open, only to be stopped by Delighted Rokusuke, who explained the situation to them. When Delighted Rokusuke ran away, he gave chase instantly. While looking around in the garden, he was attacked by Angry Rokusuke, although he avoided it. Sanzo dueled with him for a while and knocked off his opponent's weapon, but was hit when Angry Rokusuke punched him, because he didn't dare to use to his sword to block it, which could tear up the other's hand. It was then revealed that Sanzo was troubled about why Fuji tried to keep a distance from him, something he never made an effort to find out before. After Angry had been restrained by Hades-sensei, he confessed that he felt blame as he saw Delighted Rokusuke, who reminded him of his younger brother when they were still close. When Hades-sensei surmised that Fuji refused to talk about his problem was because it was something he could solve himself, it was Sanzo who realized that his brother was given the Fuji family crest Haori-hakama, which was the proof of succeeding the household, something his brother greatly resented and made him vulnerable against the disease demon. Together with Hades-sensei, he fought the disease demon's true self and helped Hades-sensei absorbed it. He waited with the visitors and the Fuji household servants until his brother woke up after being rescued from the demon. Only when he made sure that his brother was okay did he pass out due to panicking to the very limit and shorting out, a trait Fuji saw as machine-like. When he found out that Fuji had no memory of being possessed by a disease demon, he got furious and forced the latter to kneel until he remembered everything. The brothers had a little talk near the end of the arc, in which Sanzo told Fuji that he didn't have to entirely rely on him, but at least remembered that he wasn't his enemy. Sanzo also briefly appeared in chapter 47, in which he expressed deep gratitude to Hades-sensei for looking after his brother.
Power & Abilities
Sanzo is a black belt in Iaido, or Iai, a modern Japanese martial art that involves the smooth, controlled movements of drawing the sword from its scabbard, striking an opponent, removing blood from the sword, and then replacing the sword in the scabbard.
Rokusuke is Sanzo's younger brother, and even though the two were very close in the past, they slowly grew distant from each other when the younger acquired the habit of giving up. Because Sanzo is an "examplary Fuji", he is the exact opposite of his carefree and lazy brother, making it even harder from them to get along. After he had rescued his brother from a disease demon with Hades-sensei, their relationship grew better in some way, but he is still often made fun of by his brother for his early receeding hairline, which he, apparently, was also troubled by.
Hades-sensei is the nurse of the school Sanzo's brother goes to. Ever since Hades-sensei helped him rescue his brother from a disease demon, he has been holding very deep gratitude towards him.
"We're incompatible. But, I'm not your enemy. Don't forget that."
- In Kanji, Sanzo means "mountain", while Rokusuke means "the base of the mountain".
- Sanzo had a girlfriend, although he probably broke up with her in order to marry the person who was engaged to him, because it was a tradition in his family.