|“||Why is it Kyo...?||”|
—Chapter 023, to Misao
Sho Usui [ 烏水 祥 / 僧正 ] is Kyo's older brother, and was originally the heir to the Tengu Clan. However, once the clan realized his cruel and abusive nature, Kyo became the heir and Misao became his fiance in turn. While he seemed to despise Misao, hating that she chose Kyo over him, he shows an emotional side in later chapters, saving Misao from being crushed to death inside a storage house. He is brought back to life by the efforts of his former attendant Roh afterwards.
In the last battle between the two brothers, he is killed but warns Kyo that he wouldn't be like him and kill Misao, implying that he read the last pages of the Immortal Fruit Record.
Sho looks remarkably similar to Kyo, which was incidentally Misao's first thought upon seeing him. 
A notable difference though is Sho's longer hair and in later chapters, an eyepatch.
The first impression one would have of Sho is his mild and gentle mannered character, however, this surface image is quickly shattered as even Kyou notes that he can't pretend forever.
Sho is in actuality a frighteningly cruel, calculating and cold person who will use and then throw away anyone and everyone around him.
But he is not all that simple either, as he is quite the complicated character, being able to show rare displays of emotion such as regret and debatably even an odd form of affection.
As the first-born, Sho was originally the heir apparent and next-in-line to be the Head of the Tengu clan. However, the status quo would be shaken when his younger brother, Kyo met the Senka Maiden, Misao Harada, and decided to challenge him for the position in order to have the right to marry her.
Before this, however, Sho was kept separate from the other children as he had the duties and heavy responsibilities of becoming a "perfect heir," meaning extreme tutoring and constant supervision. This may have played into his eccentricity at the start.
He started to exhibit chilling mannerisms at a young age as well, such as violently killing a puppy that bit him. Sho himself would note that this event started people's gradual fear and ostracization of him.  Though people were somewhat forced to attempt ignoring it since he was the heir and a remarkably talented one, even at such a young age.
It would be a while later before he (and his "spare tire") were sent away from the village to become familiar and establish contact with the Senka Maiden, Misao, when she was still a young girl.
Sho had mastery over spiders and snakes, controlling them to suit his will.
He also learned how to see images in a pool of water and communicate through it, picking up the ability by watching his cousin, Ayame.
When Misao was a young girl she would always visit the household next door to play with Sho and Kyo. Her memories were somewhat foggy, but it was in fact Kyo who she was always spending time with. At one point, Sho slapped Misao after she had made him a mud pie because she had given one to Kyo before giving one to him . Sho was supposed to take Misao for his bride but his brother, Kyo, surpassed him in order to become the clan leader due to his desire and love for Misao. Kyo becoming the leader in place of Sho allowed him the right to marry the senka maiden. Sho despises the fact that Misao chose Kyo over him, and manipulated Misao's memories to confuse her emotions. Ten years after Kyo and Misao reunite, Sho kidnaps and attempts to rape Misao to overturn Kyo as leader and make him never want her. Sho had also planned to devour her, but Kyo finds her in time to rescue her. Sho is then incarcerated in their home village. It was revealed later to the two that Sho was the one who sealed up Misao's memories. It is said in volume 13 that Sho loves Misao and wishes she was his instead of Kyo's.
Kyo is Sho's younger brother and the one who took the title as Leader of the Usui clan. Sho hates that his brother was always there in case he failed. He calls Kyou "the spare tire" or "back-up plan".
The only person who believes in Sho and whose attitude for him did not change even after the thing that he did to the other clan members. Sho didn't like the fact that Ayame and Sagami (Ryo) had gotten married because it lead him to feel more isolated.
Sho knows about Hoki's past so he uses that to his advantage when he tries to take over the clan. He wants Hoki to join his side so they can both take over Kyo.
Sho is the one who removed his seal when he wanted Kyo to lose all his protectors . Sho kept him as a hostage until he was ready to set him out on the village.