Kyoya Hibari, commonly referred to as Hibari, is one of the major characters in the Katekyo Hitman Reborn! series. He is the leader of the Namimori Middle Disciplinary Committee, a group of delinquents who are all loyal to him. He was nominated and accepted as the tenth generation Cloud Guardian of the Vongola Famiglia. He is often seen napping on the rooftop of Namimori Middle School, alongside Hibird.
Hibari is a young man with an average height and short black hair with a fringe that joins at the center of his face. He has narrow gray eyes, often intimidating those who see them. He bears a striking resemblance to the first generation Cloud Guardian, Alaudi, as well as the Arcobaleno, Fon.
Hibari's most common outfit is his Disciplinary Committee uniform. He wears a white long-sleeved shirt, black pants, black shoes, and a black gakuran top worn on his shoulders, with the committee's armband pinned on the top's left sleeve. He also wears the standard Namimori Middle School summer uniform, along with the armband. During the Varia Arc, Hibari wears the winter uniform, also with the armband.
Ten-years-later Hibari has changed to wearing a simple black suit, with a purple shirt and black necktie. His hair is also shorter, having been cut to appear messier, and with hardly any fringe. When not training or fighting, he would wear a black kinagashi.
As stated by others, Hibari is a scary character with no care for the well-being of others, preferring to do whatever it takes to get what he wants. He has full confidence in his own strength and power. This often leads to his opponents surprising him, as he doesn't think before attacking. As the head of Namimori Middle's Disciplinary Committee, Hibari uses authority to assault those that get on his nerves, including his own subordinates.
He prefers to be alone and hates crowding. This leads him to beat anyone who he thinks is crowding around him too much. He is often seen taking a nap or observing students from the school's rooftop.
A rare trait about him is his love for small animals, ranging from birds to hedgehogs. He is also shown to have a soft spot for I-Pin, having accepted her Valentine's Day chocolates with a smile and not taking money from Tsuna at a festival upon seeing I-Pin worried.
Hibari is fiercely loyal to his school and its rules, going so far as to punish others for breaking them even if they aren't students or at the school, such as Genkishi.
Hibari dislikes working together with anybody due to feeling indebted and restrained. He strives to pay them back as soon as possible. He cannot stand being restrained and absolutely refuses to allow himself to be controlled.
Future Hibari is shown to be more calm and observant about his opponents, and outwardly admits to hating illusionists because of his grudge towards Mukuro Rokudo, the first person to have defeated him. His desire to be alone and attack people that annoy him still remains, though his actions are shown with more thought. Future Hibari is also seen being more respectful to Future Tsuna, showing that he has accepted him as his boss, seen in one of the flashbacks of Shoichi Irie.
Hibari's reputation as a frightening individual definitely precedes him, earning the respect and fear of many people, both present and future. He is the strongest of the tenth generation Vongola Guardians and has hardly ever lost a fight in the series. In the times he faced against Gokudera and Yamamoto, he easily defeated them in their first initial encounters, but afterward, they grew strong enough to give him a challenge, but not enough to excite him, as the only ones that could do that were Reborn and Future Tsuna.
One of the most terrifying traits of Hibari is his immense resilience and endurance. He is still able to fight despite having several broken bones and even capable of resisting Death Heather poison that was capable of stopping elephants from moving. Later on, Hibari has become very adept at using Rings although he usually shatters them after one use, due to the intensity of his flames. Hibari is capable of emitting massive Dying Will Flames with the Cloud Vongola Ring. The massive flame overloaded his Box Weapon and made the Porcospino Nuvola drunk from the flames, causing it to go out of control.
- Cloud Flame Radar: Hibari uses his Ring's Flames as a radar by thinly spreading the Flame over a wide area and using the vibrations to detect anything that enters the area. This allows him to counter illusions by using it to sense where the actual object is, as seen in his battle against Genkishi's Spettro Nudibranchi.
- Tonfas: Hibari's main weapon for combat is a pair of tonfas. It is revealed that they hold hidden compartments. The ends of the tonfas can release flails and the sides contain spikes and hooks.
- Porcospino Nuvola: Hibari's Box Weapon, nicknamed as Roll. It is a small purple hedgehog with silver spikes. Hibari uses his hedgehogs when he fights opponents he deems as weak. With Cloud Flame's Propagation characteristic, Roll is able to multiply in number and grow to large proportions.
- Porcospino Nuvola ver. Vongola: Hibari's original Cloud Hedgehog Roll is later integrated into his Vongola Box. It now appears as a Hedgehog with larger, but fewer, spikes than the other Cloud Hedgehogs.
- Cloud Vongola Ring: Won after the Vongola Ring Conflict against the Varia. Hibari wears the Ring on his right hand. He is able to open Cloud-attribute Box Weapons.
- Bracelet of the Cloud Version X: The upgraded Vongola Cloud Ring, combined with Hibari's Vongola Box animal Roll. In battle, Roll now has jewels on both his forehead and chest. He is now capable of merging directly with Hibari for his Cambio Forma.
On November 7, 2007, a character CD entitled "Sakura Addiction," featuring Mukuro and Hibari, was released, and became the most successful Reborn! character CD, debuting in ninth place in the Oricon charts. The single reached its peak at seventh place, but remained in the chart's Top 40 until mid-January 2008. It contains duets and individual songs sung by both voice actors: Toshinobu Iida and Takashi Kondō. There are two available covers; both show one character as the main feature, with the other shown in the background with his back turned. The song "Sakura addiction," which was a duet sung by both voice actors, was used as the fifth ending theme for the series.
For the second annual Seiyū Awards, Toshinobu Iida and Takashi Kondō each received a nomination for "Best Musical Performance," for "Sakura Addiction."
- "Hibari" can be translated as "skylark", a species of perching birds.
- The first kanji in his name translates to means "cloud", reflecting his flame attribute and role as Cloud Guardian.
- A common shorthand of his name is "18", a combination of ((一, hi?, lit. one)) and ((八, ha or ba?, lit. eight)).
- His favorite food is traditional Japanese food and hamburger steak.  The latter which he shares with Tsuna.
- His favorite phrase is "Kamikorosu" ((咬み殺す, kami korosu?, lit. I'll bite you to death)) and "Wao" ((ワオ, Wao?)).
- In the 2007 and 2008 popularity poll for "the character I want as a groom", Hibari ranked first.
- His pride is Namimori Middle's Disciplinary Committee and the iron hammer for those who are against its order.
- Hibari seems to think that the Dying Will Flames are fueled by irritation instead of resolve, due to him thinking that both were the same thing.
- Hibari shares the same seiyuu, Takashi Kondō, as Alaudi and Fon.
- According to Kusakabe, Hibari cannot stand drinking alcohol.
- Even though he is still in Namimori Middle School, Hibari apparently owns and rides a motorcycle.
- Hibari was featured on the cover of the eighteenth volume, the volume number is the same as his shorthand.
- Due to a previous infection with the sakura-kura disease (which was later cured), he feels uneasy whenever around cherry blossoms and loses his will to fight and even refuses to even talk about it when Haru bring it up as a subject in Haru-Haru Interview.
- He lives in a large traditional Japanese house with the same style as the one the Foundation built in the future.
- Fon inferred that he and Hibari were related, but changed the subject saying that Hibari would get angry if Fon explained the relationship.
- In Everyone's One Day Activities, he made a new room in Nami-Middle for all Hibirds that he owns.
- Amano, Akira. Katekyō Hitman Reborn! Vongola 77. Tokyo: Shueisha. 2007. Print. p.56
- Amano, Akira. Katekyo Hitman Reborn!. Tokyo: Shueisha, 2004–2012. Print. Vol. 42: Chapter 409
- Amano, Akira. Katekyo Hitman Reborn!. Tokyo: Shueisha, 2004–2012. Print. Vol. 31, Haru's HaruHaru Inteview 28, "I know everyone is curious about our relationship, but if I said what the relationship is, he might get angry. Let's change the subject." -Fon
- Katekyo Hitman Reborn! anime: Episode 019