The Beltline Monsters are fictional beings within the GetBackers manga. They are immortal, soulless beings that hail from the Beltline, with each one of them possessing monstrous strength. They are feared throughout the manga, and known to be extremely formidable foes.
The Beltline, the most dangerous area of the Limitless Fortress, is ruled by Der Kaiser a mysterious man and Ban's father. The citizens of the Beltline are said to be immortal and imperishable, and they 'will rise back from the dead every time they are attacked'. Every single person from the Beltline has a hideous death-like appearance and a frightening strength.
In Volume 29, the Beltline Monsters are officially introduced. Ginji explains that the Beltline Monsters have no humanity. They are practically immortals, carrying ridiculous strength. Kazuki confirms Ginji's words. Kazuki explains that he once went to the Beltline in order to uncover the secrets of Babylon City, but he was forced to flee due to the overwhelming power of the residents of the Beltline.
In the Queen's Cup, Help demonstrated its powerful logic against Maria Noches, only for Ban Mido to step in and defeat it. Akabane stepped in, and effortlessly defeated the Beltline Monster that once defeated Kazuki. Himiko defeated her Beltline foe, and Divine Intervention saved Ginji from his.
Later on, when Ban and Ginji entered the Beltline, the residents there proved to be too overwhelming for the GetBackers duo. Through a bit of training from Paul, the GB Duo as well as the others were able to treat the Beltline Monsters as mere cannon fodder.
The Beltline Monsters were not born, but in fact, creations of the Infinity Fortress itself. They have no immaterial soul. In other words, they only exist in the sense that they are "Here." They don't fear death since they were never born, and since they don't fear death, they will not die. This is their logic. When Ban Mido explained their logic, he knew that he only had two options: erase the Beltline Monster from existence, or send it back to where it came from.
The Beltline Monsters do not exist at all in the material sense. Juubei himself, who has heightened senses could not sense anything in the arena other than Ginji. There was nothing but a gaping hole in front of him. Saizou himself could not sense that the Beltline Monster actually existed. MakubeX's calculations showed that Beltline Monsters had no readings for mass or caloric value.
The Beltline Monsters are in actuality conceptual vacuums. MakubeX explained that they are the concept of Vacuum. They are true vacuums, devoid of even the smallest particles. In short, they don't even exist, as mentioned before. They simply are "Here."
Strength, speed, and the ability to read a person's actions are useless against a Beltline Monster. They fight based on their own logic. Their skill, speed, strength, and intelligence are all at top level. A Beltline monster merely responds in a ‘logical’ way each time his opponent attacks. Mere magic will not work. Relying on reading their moves will not work. They fight as if it's an easy logical equation.
- The Residents of the Beltline are not affected by the bounds of time and space, as seen when Help was able to effortlessly impale Maria from behind. Maria Noches exists outside of the space-time.
- Killing blows do not affect Beltline Monsters, seeing that they are immortal. They will simply get back up over and over again.
There are actually quite a few variations of Beltline Monsters.
- There are "Fake" Beltline Monsters, in which their power comes from Houjutsu. They were never born, and possess no souls, but they exist.
- He carries a sharp spike on his arm, which he used to impale his opponent in the heart from the get-go.
- He can also cause an array of spikes to impale his opponent from the ground, each spike towering above 7 feet.
- He was shown to be able to bypass magical defenses that reflected attacks, and chew right through the flesh of an opponent, leaving not a hint of blood. It is a mere matter consumption attack.
- He himself explained that he was never born. One day, he was simply here.
- He believes that existence has no meaning.
- There are "Real" Beltline Monsters, in which they simply don't exist.
- He was able to take a full body plasma burst from Raitei, and was completely unaffected. It was noted that Raitei's power is so powerful that it can cross through dimensions, but yet it had no affect on Der Henker.
- When he opened up his cloak, and entire cosmos was seen within in. Raitei's lightning went straight into it.
- He can utilize his existence and pull an infinite amount of energy into a vacuum.
These are random Beltline Residents that proved to be too much for Ban and Ginji. They utilized swordsmanship in their method of fighting.
- They can launch dreadful waves of light onto their opponents.
- There are Ura-Fuuchouins, in which their power comes from Cursed Threads. The Ura are merely residents of the Beltline, and they were actually born. However, they are given status as Beltline Monsters through the Cursed Thread.
- They know every technique that Kazuki knows, except for his ultimate attacks.