Bass

First appeared: Volume 2 - Movement 9

The Hell King, he is the number one mazoku general. He has incredible magic power, and is actively searching out for both Pandora's box and it's key. His name derives from a bass guitar, as all the mazoku generals are named after rock instruments.

Bassoon

First appeared: Volume 1 - Movement 4

Haunting the inhabitants of the city of Tenuto, this monster is also running loose and causing havoc to the humans. His name refers to the woodwind instrument bassoon.

Chestra (Kestra)

First mentioned: Volume 2 - Movement 7

First appeared: Volume 10 - Movement 40

The Daimaou, or Demon King, Chestra was sealed away within Pandora's Box. He is the father of Hamel, and husband of Pandora. The name derives from Orchestra, because when 'Daimaou Chestra' is said together it sounds vaguely like 'Daima-Orchestra'.

Clari Net

First appeared: Volume 5 - Movement 22

Sforzando's archbisshop and leader of it's army, the magikorps. A mostly calm and mature person tough he has a soft spot for his sister Corr Net. He will fight with every ounce of strength to defend Sforzando and Queen Horn, to whom he has unbreakable devotion to ever since he saw her as a child. In battle, he wields powerfull magic, but can also use his own kinds of teleportation magic. His name is based on a Clarinet, a woodwind instrument.

Corr Net (Cornet, Coro Net)

First appeared: Volume 8 - Movement 34

Clari Net's 13 year old little sister, she has the same talent for magic as her brother, if not more. Her mother died after she was born (Her father's state is unknown, but he is probably deceased as well), so she was raised by Clari, who spoiled her completely rotten. She has a silly girlish crush on Hamel and trys to eliminate her 'love rival' Flute. In battle, she uses her floating cross and magic to defeat foes tough she is also capable of wrestling down monsters. You could think that her name is based on a Cornet, a trumpetlike instrument or maybe a Cornett or Cornetto wich is a woodwind like her brother's name, but in Watanabe's profile, the instrument she is a Bass trumpet.

Drum

First appeared: Volume 2 - Movement 9

The Dragon King and number 2 in rank. Drum relies on brute strength to fight, though he has the command of a score of dragons that live within his body. His name comes from the instrument drums.

Fagotto

First appeared: Volume 1 - Movement 5

The undead comander of a force of skeletal soldiers, Fagotto enslaves the people of the minning town of Legato to work to their deaths. He meets his untimely death at lighting speed. Fagotto is the italian name for the bassoon.

Flute

First appeared: Volume 1 - Movement 2

The unknowing princess of Sforzando takes a leave from her small home town Staccato to aid Hamel on his quest North. Her name as spelled refers to the musical instrument Flute.

Guitar

First appeared: Volume 2 - Movement 9

The Warrior King, and number four in rank. Although an excellent swordsman, Guitar is the most cunning of the mazoku generals and will most often manipulate from the shadows. His name comes from the instrument guitar.

Hamel (Hameln, Harmel, Hamelin)

First appeared: Volume 1 - Movement 1

Our great Hero, who isn't that great and gentle. His name is from the tale The Pied Piper of Hamelin. Instead of using a pipe, our hero uses a gigantic Violin.

Lute

First appeared: Volume 2 - Movement 9

Hell King Bass' misterious marionette. Lute is the young boy carrying the monster general's head; possessor of great and powerful magic, albeit he does not speak or act of his own. As you could have guessed, his name comes from the instrument Lute.

Mouthpiece

First appeared: Volume 3 - Movement 14

The feared moster that dwells on the Fine mountains. Mouthpiece protects the path north to the Northern Capital Hameln, by using the multiple spikes he possesses. His name is in fact the mouth piece of an aerophonic instrument such as a trumphet or trombone. On wind instruments the mouthpiece is that part of the instrument which is placed in, or next to, the player's mouth.

Raiel

First appeared: Volume 2 - Movement 6

Self proclaimed Warrior of Love, Raiel is a long lost childhood companion of Hamel, hunted by shadows of the past. Popularly believed, Raiel is a form of wind-up piano/organ that plays by itself.

Ocarina

First appeared: Volume 2 - Movement 9

Hawk King Sizer's loyal servent, Ocarina has the form of a blue white crow, much in the manner of Oboe. She is the advisor and informer for the Hawk King, bearing her name from the aerophonic instrument ocarina.

Oboe

First appeared: Volume 1 - Movement 1

Hamel's companion. Why he's traveling with Hamel, is yet to be unrevealed. Name comes from the instrument Oboe.

Pandora

First mentioned: Volume 1 - Movement 1

First appeared: Volume 4 - Movement 16

Hamel's mother. Clearly based on the story Pandora's box. But, it's also a string instrument invented in England 1562 (Also called Bandora), Pandora (disambiguation).

Percuss

First appeared: Volume 5 - Movement 21

Queen Horn's steward. He has mastered teleportation magic, wich he uses quite often to get around the castle quickly. despite his rather snobbish and elitist attitude towards Hamel and his non-Sforzandon companions, he is very dedicated to the Sforzando royal family and would do almost anything to keep Flute at Sforzando to be the princess. So far, he has not shown any combat skills. His names comes very likely from the musical term percussion, a general term for instruments that are struck, rubbed, shaken or scraped.

Sizer

First appeared: Volume 2 - Movement 9

The Hawk King, and number 3 in rank. Although with the mazoku Sizer is not actually one herself. Instead she possesses angel blood, which allows her to open Pandora's Box, making her invaluable to the mazoku. She, like Raiel, is a spirit summoner and plays Wagner's 'Ride of the Valkyries' on the flute in her scythe to summon nine Valkyries. Her name derives from the synthesizer.

Syrinx (Sphynx)

First appeared: Volume 2 - Movement 9

King Syrinx ruler of Dal Segno, confronts the General Monsters as they arrive upon his nation. Father of Trombone, he's the caster of the Scissor Slash/Cesar Slash; Trom's posterior sword technique. His namesake, the syrinx, is another name for a panpipe/pandean pipe.

Tuba

First appeared: Volume 1 - Movement 3

Claiming ownership over Staccato Village and dining on its inhabitants, Tuba is one of the earlier enemies Hamel and Flute encounter upon their meeting. His name belongs to the instrument tuba.

Trom Bone (Trombone)

First appeared: Volume 3 - Movement 13

The young king of Dal Segno sets upon a journey to avenge his fallen parents against the Mazoku. He has a bratty and loud personality. The name derives from the aerophonic trumphet-like instrument Trombone.

Trum and Pet

First appeared: Volume 5 - Movement 22

A dastardly duo of dragon demons in disguise (try saying that 5 times fast, though I know monster is the proper term). They are orginally sent to Sforzando to serve as spies, but decide to break orders for delusions of grandeur, and set themselves on the task of defeating Hamel and party. Events are turned in the monsters' favor, until Clari Net comes and easily dispatches this pair. Obviously their names are the separated form of the word Trumpet, a popular brass instrument.

Viola

First appeared: Volume 1 - Movement 1

The young boy Hero saved in the very first movement. His name Viola comes from the instrument with the same name.

Vi Olin

First appeared: Volume 6 - Movement 26

A somewhat excentric inventor who lives in the mountains outside Sforzando and has crafted Hamel's ultra large violin as well as Pandora's box. He also has made several other devices to seal away monsters, but pandora's box is still his greatest creation. Tough he acts rather silly and nonsensical, he is actually quite wise and intelligent during one of the rare moments he's serious. His name is quite obviously derived from the Violin.

Firebird

First appeared: Volume 6 - Movement 27

A fire spirit that takes the form of a bird. Raiel summons this spirit by playing a piece from Igor Stravinsky's ballet (or perhaps the suite?) "The Firebird" (there is no certainty wich score he plays as there are several ones like appearance of the firebird and dance of the firebird). The firebird in question actually comes from russian folklore, tough the one summoned by Raiel has a closer resemblance to a Phoenix. As you probably deduced from it's name, the firebird simply burns it's foes to a crisp by flying into it.

Snow spirits

First appeared: Volume 3 - Movement 12

Raiel's dance of spirits summons 6 snow spirits who take the shape of snow dragons. This is cited to be his certain kill technique, wich is most likely true as with it, he would have managed to overcome Hamel during his first demonic transformation in the manga were it not for a unfortunate hand injury. 'the dance of blessed spirits was a piece by Christoph Wilibald (Von) Gluck called:"the dance of blessed spirits" in the opera: "Ofea ed Eurodice".

Valkyries

First appeared: Volume 4 - Movement 20

Whenever Sizer performs Wagner's Ride of the valkyries, she summons the valkyries to her side, 9 holy spirits who take the form of warrior women. They are fierce fighters and with their help, Sizer has been known to destroy entire armys. Their personality is dependant on sizer's mood, they have been seen as merciless and cold warriors but have also appeared quite girlish outside of battle, repeatedly flirting with the male members of the group or stating how cute something or someone looks.

Each Valkyrie have their own name, in the following order: Gerhilde, Helmwidge, Waltraude, Schwertleite, Ortlinde, Seigrune, Gringerde, Rossweisse and Brunhilde.

The first eight of them are summoned by Sizer to fight alongside her, while the 9th valkyrie has the ability to become her armour, allowing her to conveniently regain her armour should it be broken. All the valkyries also seem to possess the ability to mimic Sizer's looks.

As you would suspect the Valkyries are based upon the Norse myth of similar name. They were the ones that chose the souls of fallen heroes and returned them to Valhalla, where they would become Einherjar, basically warriors in Odin's army for when the end of the world, ragnarok, would happen. there are little to no accounts about valkyries being warriors,in fact they were also maids who served aforementioned einherjar, tough in modern culture they are often depicted as warriors.

It should also be noted all of Sizer's valkyries' names are used in the same opera as Wagner's ride of the valkyries.

Water spirit

First appeared: Volume 4 - Movement 16

A water spirit in the form of giant water serpent is summoned. It's not sure if this is simply an alternate version of "dance of the spirits" or a different spirit as the name of the score used to summon it has not been disclosed yet. The spirit's form is probably based on mythological water serpents like Leviathan.