General Grineed, also known by the titles the Clever Honcho of Deep Green or the Bloody Beast, is a powerful antagonist and a seven-star Vandel. His appearance is largely insectoid, with a tough, shell-like skin and a small horn on his head that reportedly grows and shrinks according to his emotional state. He is deeply self-conscious about his natural form, to the point of bathing daily in a special mixture to conceal it. When he sheds his skin, however, his body becomes even more beetle-like and his horn transforms into a sharper, sword-like weapon.

On the surface, Grineed aspires to be a cool, intellectual, and emotionless Vandel, believing this to be the ideal demeanor for his kind. He considers himself a rival to Beltorze, another powerful Vandel, and strives to surpass him in every way. However, this composed exterior is a fragile mask. Grineed possesses an extraordinarily short temper and can be driven into a murderous rage by the slightest provocation, such as being addressed in an overly casual manner like dude. Once his anger is triggered, he becomes a brutal and indiscriminate force of destruction, attacking anyone in his vicinity, including his own allies and monsters, without a shred of mercy. This violent nature is something he seems to be aware of and, to some extent, laments, as it prevents him from being the calm, collected figure he wishes to present to the world. He harbors a general hatred for humans, often referring to them as trash.

Grineed's primary motivation is to increase his power and status. His most explicit goal is to acquire an eighth star, which would elevate him to the highest echelon of Vandels. To achieve this, he engages in complex schemes, such as having his underling Kissu research ancient ruins to uncover secrets for creating new monsters from earthly materials like rock. By creating these monsters, he hopes to gain independence from the Dark House of Sorcery and earn another star. Beyond raw power, his actions are also driven by a deep-seated need for respect and to improve his image, as he feels he is neither liked nor respected by his peers.

In the story, Grineed serves as a major adversary for the protagonist, Beet. His domain is known as the Black Horizon, where he rules over several minions. These underlings include Frausky, Rozzgoat, Ventura, Dangowl, and the reluctant servant Kissu. To ensure their loyalty, he forces them to wear bracelets that allow him to inject them with poison or use a divine attack as punishment for disobedience. His relationship with Kissu is particularly significant; when Kissu betrays him, Grineed flies into a catastrophic rage, destroying his own castle and killing most of his subordinates before attempting to force Kissu to return to his service. He also has a noted rivalry with Beltorze, and his encounter with Beltorze's phantom was enough to make him back down from an attack, though he then took out his frustration on others.

Grineed undergoes a significant, if final, character development during his last battle. When he is cornered by Beet and his friends, he sheds his skin, unleashing his full, uncontrollable power in a rampage. In this state, he is virtually indestructible and immensely strong, capable of using a technique called Peak Infuriation or Fierce Wave of Infuriated Steel, where he vibrates his muscles with Dark Power to emit a massive shockwave that destroys everything in its path. His career comes to an end when Beet uses the Boltic Axe to cut off his horn, leading to his defeat. In his dying moments, he returns to his calmer state and reveals that his body contains a powerful bomb filled with Dark Power, set to self-destruct upon his death. This final act, meant to destroy his enemies, is a testament to his calculating nature, even in defeat.