Lisa Oakwood shared a strong childhood bond with Luke Ainsworth. Aspiring to become a knight, she displayed traits like Cecily Campbell's, including a dedication to protecting others. While exploring a cave tied to the demon Valbanill, she was killed shielding Luke from harm.

In her final moments, Lisa Oakwood formed a demonic pact, sacrificing her existence to create a demonic entity inheriting her appearance. This entity would fulfill her wish to protect and care for Luke indefinitely. The pact birthed a demon taking Lisa Oakwood's form, retaining her youthful physical characteristics: blonde hair, purple eyes, and elven ears.

This demon, known as Lisa, manifested with the biological age of a three-year-old while carrying seventeen years of existence. She possesses the ability to generate large magical fireballs, essential for Luke's blacksmithing work, particularly forging katanas during combat. Lisa serves as Luke's live-in assistant, managing household duties and aiding his forge operations.

Her personality is characterized by kindness, politeness, and unwavering devotion to Luke. Her existence revolves around fulfilling the pact's purpose. She expresses profound love for Luke and willingly prioritizes his needs. However, she experiences emotional conflict regarding her identity as a manifestation of Lisa Oakwood's sacrifice. She perceives herself as a duplicate carrying the burden of Luke's past trauma, acknowledging her presence reminds him of his loss. Despite this pain, she explicitly states her desire to remain with Luke permanently.

Luke reciprocates protective feelings, having vowed to safeguard her. He initially believed his own actions created her through a death song, though the pact originated from Lisa Oakwood's sacrifice. Luke's glass eye serves as a physical reminder of their connection, created using his original eye.

Centuries after Valbanill's sealing, Lisa exists unchanged in appearance due to her demonic nature. She becomes teacher and guardian to Luke and Cecily Campbell's descendants, preserving their legacy. After three hundred years, she applies her blacksmithing knowledge to forge a sacred sword. This act releases Aria from her sacrificial role while maintaining the seal on Valbanill, fulfilling Cecily Campbell's promise.

Lisa maintains significant relationships beyond Luke, including a close friendship with Cecily Campbell and the demon sword Aria. Her interactions with Cecily involve notable expressions of admiration, particularly regarding physical attributes, during their initial encounters.