50 years after the hero and her party defeated the demon lord trying to conquer the land, a new threat looms on the horizon. Another war is brewing as a malevolent force seeks to conquer the world.

Meet Killian, the mysterious figure concealed behind the mask of the legendary mage, Zero, who was a vital member of the hero's party. In his day-to-day life, Killian assumes the role of a seemingly feeble healer, attracting the adoration of countless women. But now, the time has come for him to step out of the shadows and secure the peace his party once brought to this world.

Unlike his past role as a mere sidekick, Zero has evolved into a formidable force, surpassing all expectations. As Zero, he becomes the world's savior, while continuing to masquerade as the unassuming healer, Killian.

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Warning: Smut, NTR, and Yuri actions.