The Fifth Fist of the "Eight Fists League". He lives for the music and composes using his battles as inspiration for the melodies. Later he becomes Niijima's personal guard and a part of Shinpaku Alliance.
Hibiki Kugenin or Siegfried as he is referred to as was the Fifth Fist of Ragnarok. He is also called "the immortal composer" due to the fact that he composes music by using his battles as inspiration for his melodies. He has a tendency to hum or sing classical music during his fights and his attacks are named after different music scores and compositions. Like his namesake, he appears invincible, always getting back on his feet after taking a severe beating. This is actually due to his fighting style which uses counters and dodging an opponent's attack by the slightest margin. As such, he usually falls down on his own to fool his opponents. He is later defeated by Kenichi after being hit by a powerful punch Kenichi created himself. After their battle, he goes on a journey to find himself. Niijima later convinces him to join the Shinpaku Alliance in Battle 110, where he acts as the Alliance's combat leader, but mostly as Niijima's personal guard. In Battle 130 he can fight of Kensei's anesthic just by will power. A job he takes very seriously threatening even his own team mates if they go against Nijima who he calls his "dear demon king". He tends to only dodge attackers until Nijima orders him to attack and even feels pride if he was able to help Nijima in anyway, even when Nijima used his unconscious body as a human shield.
He is named after Sigurd, a hero in Norse mythology.
As the threat of Yami becomes apparent, Siegfried travels to Tibet for further training. He sky dives into the arena just in time to help Shinpaku which is short-handed due to injuries, and is outnumbered fighting the Capoeira team in the D of D tournament. His training has made him virtually unbeatable, he is capable of dodging two people attacking at the same time with little effort, he can even turn his head a whole 180 degrees due to his training, a fact that makes Kenichi doubt his humanity. It is stated in this fight by Shio Sakaki that Siegfried specializes in a Go No Sen (striking last,hitting first) style of fighting and he is almost a master class in this technique. He could have actually defeated the entire capoeira team including the leader by himself, however he hesitated because he was waiting for Niijima to order him to attack, after shocking everyone with his newfound power he collaspes from severe lack of sleep due to him searching for the Shinapku Alliance non-stop for three days straight. During the fight Siegfried claims that he has no more weaknesses not even a leaf which is a reference to the legend of Sigurd. The Elder claimed that someday, Siegfried will definitely become a master class fighter.
It is also revealed in the manga that Siegfried is very wealthy. He is solely responsible for providing all the funds necessary to reconstruct and renovate the Shinpaku Alliance's headquarters.