Hibiki Kugenin, commonly called Siegfried, is one of the supporting characters of History's Strongest Disciple Kenichi. He was the Fifth Fist of Ragnarok and is currently one of the leading captains of the Shinpaku Alliance. He is also called "the Immortal Composer" due to the fact that he composes music by using his battles as inspiration for his melodies.
Siegfried has a tendency to hum or sing classical music during his fights and names his attacks after different music scores and compositions. Siegfried is most often singing from ether 'Night on Bald Mountain' by Modest Mussorgsky, or an exert from Mozart's 'Requiem' as the music played in the background. He demonstrates great loyalty to whatever he associates music with and gets angry at those who make him lose track of his music. His talent in music, including the piano, violin, tambourine, and assumingly the bassoon, landed him a scholarship at a well-known school for music, and has even been consulted for musical advice on the bassoon. This musical loyalty carries onto his defection from Ragnarok to Shinpaku Alliance, before which he stated his respect for Niijima and desired to hear the melody that the latter had "composed", and during which he comically explains in a song that he sat by the sea mourning the limit to his music until "Niijima-sama" came and played a flute-accordion, convincing him to join Shinpaku, the motive for which he states that he has heard a beautiful melody. His obsession with music carries further to his reconnaissance during the camping trip, when he strains from being unable to write music until he hears Tochumaru and his animal friends playing some music nearby.
Siegfried is Thor's best friend, as the two are very close to one another and have known each other since their times from Ragnarok. They always have each others back.
There's a running gag that has Sieg noticeably display bizarre and even creepy or gross techniques that would leave normal fighters dead from such moves, such as when Lugh seemingly snapped his neck, Siegfried snapped it back into place, prompting Kenichi and Niijima to wonder what training in Tibet he went through. He also is able to move his head in a 180 degree motion like an owl, creeping out his opponents several times. In battle, as noted by Niijima, when Sieg believes he's right, he's quick to prove it by fighting in battle.
With music as motivation for his loyalty, Siegfried demonstrates his loyalty to great, even extreme extents. He tried to swim across a river with three broken ribs to support Shinpaku in its final fight against Ragnarok, was willing to sacrifice his life for the rest of the Shinpaku members while being strangled by Li Raichi, and searched for it for three days nonstop during the D of D tournament, all for his "Dear Demon King" Niijima.
It is also revealed that Siegfried is very wealthy. He is solely responsible for providing all the funds necessary to reconstruct and renovate the Shinpaku Alliance's headquarters. Siegfried also seems to have some aptitude as a magician, being able to pull a bird out of his hat. He also appears to be quite an animal lover, as he claims to have 20 dogs and cats.
Being a former Ragnarok members, Siegfried being the 5th strongest member of Ragnaok become the most powerful besides perhaps Natsu Tanimoto or Ikki Takeda . Before he when underwent extensive training for the DofD tournement, he is able to fight on par with a members of YOMI, only losing because of the opponent's sparks getting in his eyes. During his fight with Hermit, another member of Yomi who has been extensively trained by one of Yami, he was able to fight on par with him before just narrowly losing, something Hermit complimented his improved skills.
- Personal Style: Like his nickname, he appears to be invincible, always getting back on his feet after taking a severe beating. In reality, he actually falls back on his own after timing it with the minor physical contact from his opponents to fool them. This is due to his fighting style. Siegfried is one of the few fighters in the series who uses a style of martial arts that they invented. It is referred to as "Go no Sen" which means "Striking last but Hitting First". He also names most of his attacks after musical terms. As the name of his implies, this style is focused solely on strong counter, dodges, and ukemi techniques that allow him to react at the slightest margin of an attack. During the DofD tournament, it was mentioned by the leader of the Capoeria Team that by spinning at an incredibly fast rate, Sieg can imitate the actions of a heavily weighted dradle, rebounding almost all kinds of physical resistance away from himself, which makes him a very difficult person to fight overall. Nevertheless, has a critical weakness: he reqires his opponent to attack first. He generally tries to cover this weakness by releasing large amounts of Killing Intent as he rushes at his enemy to cause them to attack him on instinctively.
- Keen Intellect: Constantly in battle, Siegfried has proven himself a highly perceptive combatant. By reading his opponent's movements from a single and quick scuffle, he can determine the true nature of his opponent's fighting style and primary battle tactics. He is able to read the flow an opponent's movents to easily follow it, effectively dodging all but the fastest and unorthodox attacks. This is done by being able to percieve and analyze the faintest noises and vibrations his opponents give off from their movements, even feeling the wind shifting around him and the signals the opponent's muscles give off. According to Lugh, one of Isshinsai Ogata disciples, this is a very difficult ability to master for one who instinctively relies mainly on sight.
- Acrobatic Skill: Most of Siegfried's attacks involve him rotating rapidly to accumulate both attacking and defensive power.
- Imitation: Sieg has great disguise skills, as he dressed as Hermit as part of a plan to induce the school idol into Shinpaku Alliance , Siegfried is able to effectively imitate Hermit's movements and defeat common Ragnarok grunts while maintaining the disguise.
- Enhanced Flexibility: Siegfried's time in Tibet enabled him to achieve remarkable flexibility of the body, to the point where he can rotate his own neck at a full 180 degrees. It is thanks to this improved flexibility that he is able to survive an otherwise killing attack from a neck-snapping, able to brush it off quickly and continue fighting.
- Enhanced Endurance: In order to effectively use his fighting style, Sieg has developed an incredibly large amount of endurance to physical injuries, so much so that people are simply left in shock as to how much damage he can actually take during some of his fights. Siegfried's physical fortitude is great enough to enable him to fight against the likes of Berserker for a decent amount of time. He has also shown to fall from extremely great heights and land with taking little to no damage. He can even survive almost having his neck snapped by a member of Yomi. Kensei Ma has stated that his inner strength is impressive, and his endurance has even earned him compliments from every other master of Ryozanpaku as well.
- Enhanced Speed: The training that Siegfried received from Tibet enhanced his speed to the point where he can traverse across several meters at high speed, as seen when he intercepted the attack on Ukita after Niijima finally gave an order to defend the former.
- Genius: Despite the fact that he never received formal training from a master, Siegfried learned techniques just through observation. His abilities had increased immensely to such degree, that even the Elder commented on his talent while claiming that Siegfried would most definitely become a Master-Class Fighter.
- Singing Talent: Siegfried, giving his singing personality, is a talented singer, being able to sing in the midst of battle and at times come up with new melodies on the spot.