Asuma Sarutobi was a jonin-level shinobi from the Hidden leaf Village's Sarutobi Clan.
Asuma was born to Hiruzen, the Third Hokage, and Biwako Sarutobi. During the Academy entrance ceremony, Asuma became friends with Kurenai Yūhi. He later cheered on his classmates during the third round of the Chūnin Exams.
During the Nine-Tails' attack on Konoha, Asuma along with the other young ninja were barred from participating in the defence of the village by Kurenai's father and the other senior shinobi. A few years after the event, Asuma would become an uncle to Konohamaru. He later became a Chūnin and later a Jōnin.
Asuma was typically a laid-back individual, and did not get himself involved in things unless absolutely necessary, as seen when he decided not to help save Hinata Hyūga during the Chūnin Exams. He was a heavy smoker but despite this, he would abruptly break the habit under certain circumstances, such as when his father died, or learned that Kurenai was pregnant. Not always seeing eye to eye with his father, Asuma later came to respect his father's role as Hokage: referring to him as a great father, and was proud to have been born into the Sarutobi clan.
About seven years before the start of the series, he had a disagreement with his father and left Konoha to pursue his personal interests. During his absence, he became one of the Twelve Guardian Ninja, a group that protected the Land of Fire's Feudal Lord, indicated by the sash on his waist. During this time he developed a strong friendship with the monk Chiriku, who would go on to become the head monk of the Fire Temple. Prior to returning to Konoha to resume active military duty, he accumulated a bounty of 35 million ryō on the black market, something he seemed to be particularly proud of. After returning to the village, resumed his jōnin duties. About twelve years after the Nine-Tails' attack, seeing his classmate fall into deeper self-pity from losing Obito Uchiha and Rin Nohara, Asuma, along with Might Guy and Kurenai decided to speak with the Third Hokage, voicing their disapproval of Kakashi being in Anbu with such bitterness and suggested instead that he be re-assigned as Jōnin sensei in the hopes of restoring Kakashi's kindness.
Asuma was a highly talented and powerful Jōnin-level shinobi, having even once been part of the Guardian Shinobi Twelve — an elite hand-picked team which served to protect the Land of Fire's Feudal Lord, a role which later earned him a bounty of 35,000,000 ryō. During Orochimaru's Invasion of Hidden Leaf, he was able to kill nine Hidden Sound ninja — who were noted to have been Chūnin-level or above — with very little effort. Assisted by his student, Shikamaru, he could also fight on par with Hidan: a powerful member of Akatsuki while also protecting his team using his skill set. He also established a great record in military prowess — something which many upcoming shinobi greatly admired.
Elemental powers and other techniques
Asuma had the ability to use both Fire Style as well as Wind Style chakra nature jutsu. He would mainly use his wind-nature manipulation abilities in combination with his trench knives to increase their lethality. When tutoring Naruto Uzumaki about wind-natured chakra, Asuma explained that enhanced with it by someone with an affinity for Wind Style, the trench knives possessed enough striking power to pierce through rock. Asuma was also well-versed in ranged wind jutsu, such as the Wind Style: Dust Storm Jutsu. In the anime, it was shown that he could use his wind chakra to levitate his trench knives and control them remotely. His proficiency with Fire Style techniques was demonstrated mainly through his use of the Burning Ash jutsu to breathe out a cloud of superheated ash capable of causing third-degree burns. Because it was ash and not flame, the attack remained in the air around the target, and therefore remained potent for a longer period of time. The ash was in fact gunpowder, which could be ignited for a devastating explosion causing intense damage.
Asuma was hailed as Konoha's foremost skill in the village with close-ranged melee combat. His battle style revolved mainly around taijutsu, combined with his special trench knives to create a melee-type fighting style. These knives are made of a special metal that is capable of easily being infused with chakra. With his Flying Swallow, he could extend the blades with his chakra to injure an enemy several feet out of the blade's physical range, as well as increasing the cutting power of the blades to the point of easily slicing through trees, rocks and even iron. He was also physically strong enough to counter one of Kisame Hoshigaki's attacks using his trench knives.
When Chōji, fearing the competition, contemplated forfeiting his match during the preliminaries of the Chūnin Exam, Asuma convinced him not to by offering to take him out for "all you can eat" barbecue (yakiniku or Korean kalbi). Asuma also claimed that he'd stop the match if it got out of hand, as the other Jōnin did during Hinata Hyūga's match. Both Ino and Shikamaru noted to themselves that Asuma didn't actually help in that instance.
During the invasion of the Hidden Leaf, Shikamaru was left by himself to defend against a group of invading Sound ninja Later, just as Shikamaru had run out of options, and the nine Sound ninja were about to finish him off, Asuma appeared and single-handedly defeated the group, saving his student. After the invasion, he attended his father's funeral.
Prior to Chōji's setting out with the squad assembled by Shikamaru to track down the renegade Sasuke Uchiha and the Sound Ninja Four, Asuma berated him for eating so much and not training enough. After Chōji'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.
During his brief battle with Itachi Uchiha and Kisame Hoshigaki, Asuma managed to catch Kisame off-guard with his trench knives, leaving a cut on Kisame's cheek below the eye. Witnessing the blade made of wind chakra, Kisame switches to ninjutsu using Water Style: Water Shark Bomb Jutsu with Asuma seemingly still battle stationed with the blades. Kakashi Hatake arrived in time to copy the technique, and used it to block the attack for Asuma's own surprise. Asuma, Kurenai, and Kakashi then faced off with the two Akatsuki members, only for Kakashi to fall victim to Itachi's Tsukuyomi. Might Guy arrived just in time to stall the Akatsuki duo and buy time for the rest of his comrades who were about to get targeted by Kisame, leading to him coaching Asuma and Kurenai on the essentials on how to fight against a Sharingan-using shinobi when the pair fled to pursue Naruto Uzumaki, their true target.
At the start of Part II, Asuma and Kurenai engaged in a friendly competitive battle to test their strengths. Despite his taijutsu prowess and valient efforts, he was ultimately no match for Kurenai and her genjutsu. She effortlessly evades all of his attacks and ultimately defeats him, humiliating him in front of the entire village. Finally, she used her powers to knock him unconconcious on his knees with his rear protruding upward. The entire crowd, including his students, laughed and mocked Asuma. Kurenai proceeds to exit the cental arena, leaving a humiliated and bent-over Asuma laying on the ground in pain.
Asuma stands at the Third Hokage's grave, where he commented on how he was finally beginning to understand what the Third had taught him. Asuma confessed that he'd always been detached from Konoha, but after seeing how his father sacrificed himself for the village, he was now proud to be a member of the Sarutobi clan.
Later, when Naruto began training to master wind chakra, he came to Asuma, who was also a wind-type user, for help. Asuma agreed to give him pointers, if he agreed to pay for his team's next meal which, Naruto forgot, included Choji. Asuma was teamed up with Shikamaru, Kotetsu Hagane, and Izumo Kamizuki as members of the Nijū Shōtai. His team, along with the entire group, was 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 tracked down the Akatsuki members, Hidan and Kakuzu, at a Bounty Station, where they quickly discovered that Hidan was immortal after their first attack. The situation worsened, when Hidan's counter-attack resulted in him becoming 'linked' to Asuma through a ritual.
Hidan assumed 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 managed to break Hidan's ritual, allowing Asuma to decapitate him with his chakra-extended trench knives. Surprisingly, Hidan's severed head started to talk, uttering expletives at Asuma and then Kakuzu for not helping him. Kakuzu finally stepped in as he admonished his partner for letting his guard down, and sewed Hidan's head back onto his body. With his body restored, Hidan resumed the ritual, and impaled himself in the heart. Though the blow did not instantly kill Asuma, it was still quite fatal.
The rest of Team 10 arrived as back-up, which, combined with a telepathic call from Pain, forced the Akatsuki duo to leave. Before dying, Asuma left some parting words with his students, and smoked one last cigarette.Later, while Shikamaru exacted revenge upon Hidan for killing Asuma, Asuma appeared before Shikamaru, and congratulated him for finally defeating the immortal. After entrusting his Will of Fire to Shikamaru, Asuma disappeared in a puff of cigarette smoke just before his student finished off Hidan with a huge explosion. Also, in his memory from the flashback, Shikamaru was finally able to understand who the "King" of Shōgi was in the real world. It is the next generation of shinobi, like Asuma's and Kurenai's unborn child, and how they would learn to care and live peacefully by the great shinobi in the present day. That was why Asuma entrusted his baby to Shikamaru, as apprentice and future sensei.
Asuma was later reanimated by Kabuto Yakushi during the Fourth Great Ninja War as a military weapon for the Akatsuki's side. However, his students faced and managed to defeat him, allowing Asuma to be sealed, and later his soul was sent back into the afterlife after the Reanimation jutsu was finally ended.