Bilin Valentine serves as a Player and Royal Knight under King Kevin Valentine, commanding the mechanized Crimson Belle with the seasoned poise of a veteran leader. Her long dark gray hair and piercing eyes mirror her disciplined demeanor, forged through years of combat and strategic command.

A decade before her current endeavors, Bilin and Kevin spearheaded the Fest—a desperate campaign to annihilate the Earless. Their efforts crumbled when fellow Player Jimi Stonefree betrayed the mission, triggering a catastrophe that obliterated their homeland. Now, they scour the globe to recover lost Equipment, striving to contain the Fest’s devastating fallout.

While tracking energy signatures reminiscent of Jimi’s, Bilin intercepted Mu and Echo Rec in a besieged forest. After swiftly dismantling the Noise Sisters hunting Mu, she escorted the duo to Tremolo Technologies. Skeptical of Mu’s power to disrupt the world’s fragile balance, Bilin tested her in combat. The clash revealed Mu’s unwavering determination, compelling Bilin to grant her passage and counsel her to seek fellow Players for answers about Jimi’s past.

Bilin’s alliance with Kevin intertwines duty and personal loyalty, operating as a Battle Couple where he maintains her Equipment while they execute coordinated strategies. Their partnership echoes Mu and Echo’s mutual reliance, anchored in shared history and unspoken trust. Though Bilin occasionally peppers her speech with English phrases—a quirk shared with Kevin—her decisions remain ruthlessly pragmatic, weighing others’ motives against proven competence. This calculus led her to permit Mu’s journey after assessing both her combat prowess and integrity.