Oliver Schtrom, born Oliveira von Schtradius, headed a ducal family within the Bluesphere Empire and possessed inheritance rights to the throne. He championed reforms to improve relations between nobles and commoners, focusing on citizens' livelihoods, which fueled his popularity. This admiration, coupled with his devoted marriage to Aria – a harmonious union without concubines – provoked intense noble jealousy. They falsely accused him of human abduction and orchestrated an arson attack that claimed Aria and their unborn child.
This tragedy ignited Schtradius's transformation into a demon. Consumed by despair and hatred, he unleashed colossal magical energy, obliterating his territory. Unlike typical demons, he preserved complete consciousness, becoming the first known demon to do so. Adopting the alias Oliver Schtrom, he infiltrated the Earlshide Kingdom's magic academy as a teacher, concealing his demonic red eyes behind an eye mask while feigning blindness.
As an antagonist, Schtrom manipulated vulnerable students like Kurt von Rietsburg, inducing their demonization. He observed Kurt's battle against Shin Wolford. Later, his demonic nature was exposed during an interrogation, leading to combat with Shin. Though severely injured, Schtrom escaped. He subsequently overthrew the Bluesphere Empire, eliminating its nobility and transforming its citizens into demons.
Achieving his revenge plunged Schtrom into an existential crisis, devoid of further life goals. He grappled with the choice to revert to humanity or remain a demon. Despite initial hostility, he acknowledged Shin's magical prowess as equal or superior to his own. Unbeknownst to both initially, Shin was later revealed to be Schtrom's biological son. Schtrom and his wife Miria also had another child, Silver, who was adopted by Shin and Sicily von Claude.
Schtrom possesses long silver hair and red eyes, a trait of demonized beings. His personality underwent a drastic shift post-demonization: once compassionate, he became devoid of empathy, willing to sacrifice others for his objectives.