Leon, known as Lestion, is a vengeance-driven dream demon fixated on destroying Mistleteinn. Clad in cowboy attire, his features linger beneath the shadow of a wide-brimmed hat, a firearm always at hand. He acts through Chizuru Kawanami, a human vessel bound to him by their shared resonance with sorrow and suffering.

His past is marked by leading allies into ceaseless battles against Mistleteinn, each ending in their slaughter and his solitary survival. These losses forged an unrelenting thirst for retribution, driving him to prioritize revenge over all consequences. His primary weapon—a gun channeling ammunition forged from deceased dream demons’ despair—carries a lethal cost: firing it ensures his own destruction. Complementing this are arm-mounted cannons that discharge searing blue projectiles, enabling lethal strikes at any range.

During their final clash, Leon’s cunning tactics breach Mistleteinn’s defenses, wounding her physically—an unprecedented blow. Yet, invoking the despair-powered weapon’s full might consumes him mid-conflict. Though Mistleteinn survives, scarred but unbroken, Leon’s crusade ends unresolved, his vengeance extinguished with his life.