Twenty-two year old, Yakushi Kabuto, is quite a mysterious character. He makes his first appearance during episode 23 as a participant in the Chuunin exams. During the exams, he seems to form a trusting alliance with the Naruto group. However, when he backed out of the one-on-one combat portion of the exams, Kakashi began to notice a pattern. This was actually the 7th time Kabuto withdrew from the exams. As it turns out, he is Orochimaru's spy (notice the changes in his headband). Continuing to take the exam allows him to pick up information on the other ninja's.
One thing is for sure...Kabuto is an exceptional ninja mastering in such jutsu as; Shikon, Chakra no Mesu, Inyu Shoumetsu and more. As a child, Kabuto was found by a Leaf Jounin medical doctor. He was raised by the doctor and taught medical jutsu. It's another skill to add to his already impressive resume. The mystery surrounding this young ninja is his good vs. evil personality. One minute he may be murdering an AMBU guard and the next he is saving Hinata's life. One is never sure where his loyalties lie. Will we ever find out? Guess you'll just have to keep watching (or reading the manga) to know for sure.

Kabuto seemed innocent enough at first.

The help he gave during the Chunin exams made Naruto and team believe he was an ally.

Hard to believe he had an ulterior motive working for the evil Orochimaru.

Kabuto is much more powerful than he lead others to believe.
In future episodes, Kabuto really shows his ugly side.
Naruto proved that he was no pushover managing to immobilize Kabuto.
The fight, however, almost cost Naruto his life!