Known for his thick eyebrows, green jumpsuit, and shiny bowl haircut, Guy often refers to himself as "Konoha's Sublime Green Beast of Prey" (木ノ葉の気高き碧い猛獣, Konoha no Kedakaki Aoi Mōjū). He has many mannerisms unique to him in the series that are meant to be seen as corny and old-fashioned, a reference to common clichés of "youth" (青春, seishun) anime. Guy is also known for going on about the "Flames of Youth".
Guy has problems remembering past opponents, best seen with his frequent fights with Kisame Hoshigaki, and also his fight with the Three Ryūdōin Brothers.
Guy's "nice guy" pose.
He is best known for his "nice guy pose", which consists of giving a thumbs up, winking, and smiling with teeth so white they give the proverbial "ping". This action is often used by both Guy and Lee to indicate commitment to a statement they had just made, their highest form of a promise. Despite these odd mannerisms, Guy has shown to be capable of being as serious, ruthless and decisive as a mission's success demands if needed, as seen during the Invasion of Konoha and his battles with Kisame Hoshigaki. He is noted to be quite scary if switching to "serious", but very reliable.
Guy is on good terms with all of his students, but takes particular interest in Rock Lee, who reminds Guy of himself when he was younger; in that they were both considered to be losers and have had to earn everything through hard work. As such, Guy puts much more interest in Lee's training than Neji 's or Tenten 's, continuing to train Lee long after the others have given up for the day. Because of this, and due to Lee's unyielding desire to master the art of taijutsu, the two have developed a father-son relation that has pushed Guy to teach Lee a number of dangerous and forbidden techniques, giving the stipulation that Lee can only use them under specific circumstances. Although Guy knows of the dangers that teaching the techniques to Lee entails, Guy wishes for Lee to be able to prove himself to be a splendid ninja, and, as such, turns a blind eye to the repercussions. However, overall, Guy is a very attentive and dedicated instructor, who does everything in his power to make sure that all three of his prized students receive proper instruction in their own particular fields.
Guy, and, by extension Lee, lives his life by his own "My Rules" philosophy, which involves setting tougher goals for failure so something good comes of it. For example, he vowed to walk 500 laps around Konoha on his hands if he lost a simple game of rock, paper, scissors with Kakashi, and proceeded to do so upon losing, even though people stopped paying attention eventually. Lee's willingness to train in the same manner as Guy seems to have caused him to surpass his master's stamina, as by the end of Part I, Guy has difficulty keeping up with Lee, lamenting that he is not as youthful as he once was.
Guy's teacher-student relationship with Lee also carries distinct attributes, such as when Guy will punch Lee for a slight infraction of a rule. After Guy assigns Lee an arduous training task as punishment, meant to recapture Lee's focus and discipline, the two may then burst into tears and affectionately embrace, in brief regret for the strong blow Lee was given. Guy often attempts to act in a similar way towards his other two students, although Tenten is usually resigned and more willing to take part in his antics than the more stoic Neji.
Guy is the self-proclaimed rival of Kakashi Hatake, even before the start of the series. Kakashi, however, is indifferent to their rivalry, which annoys Guy to no end. Guy randomly challenges Kakashi to contests of skill, and has acquired a record of 50 wins and 49 losses in doing so. Given that the contests that make up this figure are so varied (ranging from Rock, Paper, Scissors to running races), this is not much of an achievement on Guy's part nor an accurate comparison of respective combat power. Nevertheless, Guy is proud of his record. Their competitions seem to, in part, be founded on the fact that the two are polar opposites. Guy has shown to be more easily excited compared to the more laid back Kakashi. He also relies mainly on taijutsu, in contrast to Kakashi's ninjutsu specialities, and had to work tremendously hard to reach his level of prowess, whereas Kakashi's natural talent and Sharingan made it easier for him to improve.
Guy can't handle sea rides and easily gets seasick when he has to travel by boat or ship. After getting over this and attempting the challenge at the Falls of Truth, Guy's "inner self" rebuked him for being too old yet still maintaining a hyper-active demeanour, adding that it is not healthy for old men like him to push themselves so hard.
