Asuma Sarutobi

was the leader of Team 10, consisting of Shikamaru Nara, Choji Akimichi and Ino Yamanaka.

Background
Asuma was born the son of the Third Hokage, and in later years would become the uncle of Konohamaru. He at some point in time had a falling out with his father and left Konoha to pursue his personal interests. During his absence he became one of the Twelve Guardian Ninja, a group who protected the Land of Fire's daimyo, indicated by the sash on his waist. Prior to returning to Konoha to resume active military duty, he accumulated a bounty of 35 million ryō, something he seems to be particularly proud of.

Personality
Asuma is typically a laid-back individual, and does not get himself involved in things unless necessary, as seen when he decides not to help save Hinata Hyuga during the Chunin Exams. He is often seen smoking a cigarette, and smokes about two packs of cigarettes a day. Despite this, he will break the habit when something is bothering him, such as when the Third Hokage died. He will also stop smoking if "something is going on", as seen prior to his last encounter with Akatsuki.

Asuma has a very close relationship with his team, even though he believes it to consist of a "glutton" (Choji), a "loud mouth" (Ino), and a "slacker" (Shikamaru). To help them overcome their underachieving natures, he attempts to use bribery and outright trickery to manipulate them into doing what he wants. This is seen most with Choji, who Asuma is frequently able to entice into action with the promise of food. Of his students, Shikamaru seems to spend the most time with Asuma and the two play Shogi or Go in their free time, though Asuma has never been able to beat Shikamaru.

It has been heavily hinted for a while that Asuma is romantically involved with fellow Jonin Kurenai Yuhi. The two appear together in most of their scenes, and the other characters make it a point to note this fact on several occasions. When Kakashi Hatake finds the two together at a dumpling shop, Kakashi asks if they are on a date, to which Asuma responds by quickly changing the subject. In a flashback, Asuma is shown buying flowers for a person he refuses to name, though Ino asks that he say hello to Kurenai for her anyway. During Asuma's battle with Akatsuki, Kurenai is often shown wondering about his progress, appearing anxious. When she learns of his death, she falls to her knees in remorse, and later lays flowers on his grave during his funeral. The truth of their relationship is made clear in Part II when it is Kurenai is seen wearing a wedding ring and it is revealed that she is pregnant with Asuma's child.

Abilities
Asuma battle style revolves mainly around taijutsu combined with his trench knives. These knives are made of a special metal that is capable of being infused with chakra. With his, he can extend the blades with his chakra to injure an enemy several feet out of the physical blade's range. When demonstrating his wind-based chakra for Naruto Uzumaki, Asuma explains that these chakra-covered blades (when utilized by someone with wind-based chakra) possess enough power to pierce through rock. During the invasion of Konoha, Asuma is able to use these blades in unison with his taijutsu abilities to single-handedly defeat nine Sound ninja without being hit once. Asuma's fighting style most resembles that of Western Boxing.

In addition to his blades, Asuma can use Fire Release: Ash Pile Burning to breathe out a cloud of superheated ash capable of causing third-degree burns. Because it is ash and not flame, the attack remains in the air around the target, and therefore remains potent for a longer period of time.

Also, in most of the Naruto games, Asuma is one of the stronger playable characters. In Narutimate Accel, one of his ougis involves him using a fire technique and a lighter to create a wall of fire. He will then use a wind technique on the wall of fire to create a fiery explosion.

Chunin Exam arc
When Choji, fearing the competition, contemplates forfeiting his match during the preliminaries of the Chunin Exam, Asuma convinces him not to by offering to take him out for "all you can eat" barbecue (yakiniku or Korean galbi). Asuma also claims that he'll stop the match if it gets out of hand, as the other Jonin did during Hinata Hyuga's match. Both Ino and Shikamaru note to themselves that Asuma didn't actually help in that instance.

Later, during the invasion of Konoha, Shikamaru is left by himself to defend against a group of imposing Sound ninja. Just as Shikamaru runs out of options and the Sound ninja are about to finish him off, Asuma appears and single-handedly defeats the group without being hit once.

Return of Itachi arc
During his brief battle with Itachi Uchiha and Kisame Hoshigaki, Asuma manages to catch Kisame off-guard with his trench knives, leaving a slight cut on Kisame's cheek. The rest of the battle goes poorly for Asuma, however, and he is nearly hit by Kisame's Water Shark Missile Technique. Kakashi Hatake arrives in time to copy the jutsu and use it to block the attack, thus saving Asuma. Asuma, Kurenai, and Kakashi then face off with the two Akatsuki members, only for Kakashi to fall victim to Itachi's Tsukuyomi. Might Guy arrives just in time to save him and the other two, and is coaching Asuma and Kurenai on how to fight against a Sharingan-using shinobi when the pair flee to pursue Naruto Uzumaki, their true target.

Sasuke Retrieval and Filler arcs
Prior to Choji's setting out with the squad assembled by Shikamaru to track down the renegade Sasuke Uchiha and the Sound Four, Asuma berated him for eating so much and not training enough. After Choji's recovery from his battle against Sound ninja Jirobo, he quickly regained his lost weight but also approached Asuma for more intense training, which Asuma agreed to with some admiration. Later, Asuma and Kurenai were dispatched by Fifth Hokage Tsunade to bring the criminal Chunin Mizuki in for questioning regarding his suspected involvement with Orochimaru. The pair arrived at the Leaf Village Maximum Security Prison only to be greeted by a swarm of released inmates, including the Legendary Stupid Brothers Fujin and Raijin. Outnumbered, the two were beaten into unconsciousness and quickly rushed to the Leaf Village hospital for medical treatment.

Part II
Asuma makes his Part II debut standing at the Third Hokage's grave, where he comments on how he's finally beginning to understand what the Third taught him. Asuma confesses that he's always been detached from Konoha, but after seeing how his father sacrificed himself for the village, he is now proud to be a member of the Sarutobi clan.

Fire Temple filler arc
When word of villages on the border of the Fire Countery have been attack, Asuma was teamed up with his former students to investigate. Upon return to Konoha, he discovers that the Sora, the son of his former Twelve Guardian Ninja teammate Kazuma was temporarily made part of Team Yamato while Sai was recovering.

Initially, Sora was rather indifferent with Asuma despite the fact that he was once an ally of of his father, but after Asuma agreed to teach him along with Naruto how to effectively use wind element chakra, Sora began to warm up to him. Quickly, Asuma realized that Sora had unusually strong chakra not unlike Naruto. As a further act of kindness, Asuma had Sora's broken tri-bladed death claw reforged with the same special material that was used to make his trench knives.

Sora unfortunately later learns the truth about Asuma's relation to his father, learning that it was Asuma who killed him. In a fit of rage, Sora attacked Asuma, using all he learned from Asuma against him. Asuma managed to incapacitate Sora, but still managed to escape.

Later during an attack on Konoha, Asuma discovered that the mastermind behind it was none other than Kazuma himself. After a heated battle, Asuma managed to defeat Kazuma. As Kazuma died talking about the future of the Fire Country, Asuma calmly said that its future will be fine, because he will see to it that its true "king" remains safe.

Hidan and Kakuzu arc
Asuma is teamed up with Shikamaru, Kotetsu Hagane, and Izumo Kamizuki as members of the Niju Shotai. His team, along with the entire group, is ordered to search for and, if possible, capture a pair of Akatsuki members who had entered the Land of Fire. Asuma and his team eventually track down the Akatsuki members, Hidan and Kakuzu, at a Bounty Station where they quickly discover that Hidan is immortal after their first attack. The situation worsens, when Hidan's counter-attack results in him becoming 'linked' to Asuma through a curse ritual. Hidan assumes a Grim Reaper-like form, causing any bodily damage to Hidan to be shared with Asuma while at the same time not hindering Hidan at all. Some quick thinking by Shikamaru manages to break Hidan's ritual, allowing Asuma to decapitate him with his chakra-extended trench knives. Surprisingly, Hidan's severed head starts to talk, uttering expletives at Asuma and Kakuzu (for not helping him).

Kakuzu finally steps in as he admonishes his partner for letting his guard down and sews Hidan's head back onto his body. With his body restored, Hidan resumes the ritual and impales himself in the heart. Though the blow does not instantly kill Asuma, it is still quite fatal. The rest of Team 10 arrives as backup, which, combined with a telepathic call from Pain, forces the Akatsuki duo to leave. Before dying, Asuma leaves some parting words with his students, and smokes one last cigarette.

Later, while Shikamaru is exacting revenge upon Hidan for killing Asuma, Asuma appears before Shikamaru and congratulates him for finally defeating the immortal. After entrusting his "will of fire" to Shikamaru, Asuma disappears in a puff of cigarette smoke just before his student finishes off Hidan with a huge explosion. Also on his memory from the flashback, Shikamaru is finally able to understand who is the king of shogi in the real world. It is the next generation of shinobi, like Asuma's and Kurenai's unborn child, and how they will learn to care and live peacefully by the great shinobi in the present day. That is why Asuma entrusted his baby to Shikamaru as apprentice and future sensei.

Trivia

 * Despite Asuma's tension between him and his father, Hiruzen, they have shown to have many similarities. They are both regularly seen smoking and have the same style beard and haircut (at least before Hiruzen went bald).