Feirune, once known as Mirei Shinohara in her past life, was reborn as a monster—an Earth Wyrm or Light Dragon—diverging from her classmates’ human reincarnations. Her former tendencies as a bully persisted initially in this new form, though she actively strove to atone for these behaviors.

As a monster, her abilities escalate swiftly, paired with sharp strategic insight. Though now outwardly bubbly and approachable, echoes of her past occasionally resurface. Discovered and nurtured by Schlain "Shun" Analeit, she bonded deeply with him, their partnership forged through mutual trust. Joining Shun’s group, she cultivated connections, including a complex rapport with Katia.

Her history as a tormentor colored early interactions, yet she sought growth, even extending empathy toward Kumoko, the spider-reincarnated protagonist. Loyal to Shun, she engaged in pivotal battles against the demon army and existential threats. Her journey balances struggles to reconcile her inherited impulses with her quest for redemption, shaping her evolving identity amid escalating conflicts.