Birth day: 8th of July
Age: Presumably around the age of 34
Height: 192cm
Weight: 80kg

Hyuuga is one of Ayanami's subordinates holding the position as Major/Lieutenant Commander of the Black Hawks and often acts as Ayanami's bodyguard. Hyuuga is recognised by his tall stature, distinctive black sunglasses, eating of a candy apple (or lolly pop), and the light smile he almost always wears on his face. He is always joking, being silly and not acting seriously. Despite this, he is very skilled with the Katana (a Japanese sword) and almost uses it to perfection. Despite his far from serious attitude he is extremely loyal and caring to his superior Ayanami, once stating that "I will do anything for Aya-tan" and that Ayanami is his "one and only king".

Despite his job as a soldier needing him to be strict and serious, Hyuuga is anything but that. He is a bit of a ditz, and views the world as being a big game and is rather frivolous in the fact that he never seems to take anything seriously. Hyuuga is playful, smiles a lot and is happy most of the time, even in life-threatening situations as he enjoys the thrill of fighting. He has a notably short attention span, is easily excited, and is easily distracted by new things, as shown when he interrupts an important conversation about the eye of Mikhail because he spots a bird and when he forgets his paperwork after seeing a new stamp. Hyuuga likes to joke around with his team mates and seems to delight in winding them all up, especially Ayanami. He is mischievous and enjoys pulling pranks and teasing his Begleiter, Konatsu.

Hyuuga is notably cheeky when speaking to those of higher rank than him, he gave Ayanami the nickname Aya-tan. Hyuuga has been shown to have a habit of giving affectionate names for people he likes: addressing Kuroyuri as Kuro-tan. Hyuuga becomes easily attached to new people whom he is interested in, as shown by his quick acceptance of the Antwort twins, Haruse, Konatsu, and is friendly to those he meets. Hyuuga enjoys meeting new people and was the Black Hawk who first thought of recruiting Haruse (implying to Haruse that he should become Kuroyuri's Begleiter), Konatsu and the Antwort twins.

Hyuuga could also be seen as quite stupid or naive. He is also quite lazy; he dislikes doing paperwork and is much happier to sit and do nothing, resulting in him getting shouted at for slacking off. Hyuuga sometimes has trouble waking up early- and as a result is sometimes late for work. He is also frequently shown yawning, and gets bored with things quickly. Hyuuga is able to do his paperwork when he is serious.

Despite his intentions being well-meant, Hyuuga often annoys others due to his sometimes overly-friendly antics, as shown in some of his interactions with Ayanami (offering Ayanami his candy apple despite the fact that he had just been eating it a moment ago).

Hyuuga is able to get away without punishment for offences that would have cost other soldiers their lives - using 'tan' to address Ayanami. ( The suffix 'tan' is normally reserved for small animals and children, and expresses that the speaker finds the person endearing, so the name would be demeaning when spoken to someone of a higher rank) However, since the omake Begleiter reveals that Ayanami doesn't like Hyuuga to call him that way, it is probable that Ayanami may have tried to punish Hyuuga at first, just that he has given up later because punishment won't work. As for why Hyuuga is not killed for that, possible reasons are that Ayanami doesn't want to lose a strong and loyal subordinate or a good friend.

Hyuuga is often very cheery and jocular when around Ayanami and seems to take delight in seeing how far he can tease him before he reacts. In one of the Drama CDs Hyuuga is shown to be the one that wants to cheer Ayanami up and to be by Ayanami's side when he is sad, and he is the only Black Hawk that notices something is bothering Ayanami. Hyuuga is utterly devoted to serving Ayanami, values Ayanami's life above his own, and becomes easily annoyed when anyone speaks ill of him or wants to harm him. In the English translation of a chapter in the manga, Hyuuga has once said 'Nii Nii' when he talks with Ayanami, and since "nii" means elder brother, it could mean that he considers Ayanami to be like an older brother. (In the Chinese translation, what Hyuuga said to Ayanami was "Sweet dream", though.)

Out of all the Black Hawks Hyuuga interacts with Ayanami the most. He was Ayanami's classmate when they were in the military academy, so he knows Ayanami for more time than other present Black Hawk members. Hyuuga is often the only person brave enough to enquire Ayanami's motives, whereas the other Black Hawks will follow Ayanami's orders without question. He is also the person who dares to do things like being late for work or escaping from work to annoy Ayanami. Despite Hyuuga's rebellious side, Ayanami trusts Hyuuga in the sense that he will give Hyuuga an answer when asked why he does something. He relies on Hyuuga to a certain extent, since sometimes he is not afraid to show weakness to him as he is the other Black Hawks. In the drama CD, Ayanami somehow softens or lets his guard down when Hyuuga mentions Yukikaze and tries to cheer Ayanami up.

It seems that Hyuuga comes from a rich family or he is rich himself. In a side story in the manga, he is swindled twenty million yen for a pot that is said to have magic power to make his dream come true. When he found out that he has been cheated, he doesn't seem to care about the money lost.

Trivia

- Hyuuga wears his sunglasses even as he sleeps (see an omake). Hyuuga also keeps multiple pairs of sunglasses in his pocket in case one pair gets damaged during battle.
- Ayanami's pet cats appear to dislike Hyuuga.
- Hyuuga is supposedly the only person who has seen Ayanami sleeping.
- Hyuuga has, or has made, an Ayanami doll (an omake in the manga).