Sekiei (spectator)

He was one of the Kumo spectators who attended the Chūnin Exams' final round.

Personality
He had proposed to his partner that he should kill Hinata Hyūga in order to take her Byakugan back to Kumogakure, meaning that he had no moral qualms about killing the young genin.

Abilities
Most of his battle tactics revolved around his use of the earth element and he used this in several ways to combat his foes, from laying skilful traps that reshaped itself, to direct combat with large enduring earth techniques and more subtle clones for diversions. He was also very analytical, noticing that Neji Hyūga was mainly a taijutsu type fighter, and used a series of techniques to bind him, thus disabling his techniques.

Konoha History Arc
When the Suna and Oto ninja attacked, he and his partner took advantage of the ensuing mayhem to kidnap an unconscious Hinata Hyūga. Their purpose was to learn the secrets behind the Byakugan. They were later pursued by Neji Hyūga, Kiba Inuzuka, Akamaru and Tenten at the behest of the Hyūga Elder, who was unsuccessful in stopping the pair earlier. Despite managing to delay the pursuing genin with a trap, Neji, Kiba and Akamaru eventually caught up with the two while Tenten remained behind. When Neji began fighting him, he was quickly overpowered. His escape however, was halted long enough for Hiashi Hyūga to arrive and intervene, successfully retrieving Hinata.

Trivia

 * Even though they tried to steal one of Konohagakure's most valuable kekkei genkai, they were not ordered to do so by Kumogakure but rather acted on their own initiatives.