Valtom is a primary antagonist in the series. His pink skin features glowing yellow patches, contrasting with his blue and yellow eyes and flame-styled hair. He wears dark grey pants, crimson boots, an orange waist cape, crimson armor, and an open hooded cloak exposing his chest. After a major defeat, large black crystalline spikes replace his right arm. Later, harnessing the Teoti royal family's power through a special golden headband with a red gem, he unleashes a drastic transformation. His body grows monstrously large, gaining increased musculature, reptilian-patterned scales on the abdomen, large black theropod-like feet, a reptilian tail, and a second crystalline arm replacing his original limb. His eyes shift to pure gold in this state.

Valtom exhibits extreme violence, rudeness, and an unyielding belief in "survival of the fittest," viewing those he deems inferior as deserving annihilation. Unlike other Teoti focused on collective survival or peaceful integration, he is driven solely by personal ambition and seizing power. He operates without ethical constraints, readily employing underhanded tactics like taking hostages—exemplified by capturing Setsura—to achieve his ends. His actions include murdering the Teoti King to steal the royal power. Throughout the narrative, he displays vanity, overconfidence, and a petulant, childish demeanor compared to other Teoti, lacking any honor, fair play, or empathy.

Within the Teoti hierarchy, Valtom operates alongside Wadatsumi and initially serves under Kannagi. His self-serving nature and refusal to align with Kannagi's peaceful approach towards humanity create a fundamental rift. His relentless pursuit of power and conquest leads to his demise, where he remains unrepentant, embodying the destructive path Kannagi avoided. Valtom's storyline concludes with his death as a psychopathic would-be tyrant, reinforcing his role as a cautionary figure representing unchecked ambition and tyranny.