The secret organization Raziel, aiming for world domination, has been attacking churches around the globe to collect the sacred relics of Christ. Amid this chaos, Maria, entrusted with protecting the relics, was quietly enjoying a solo masturbation session inside the church as usual. Suddenly, Raziel's soldiers burst in and launched an assault. Surprised, Maria instinctively fought back using karate techniques, defeating the attackers. While burdened with anxiety over her sacred duty, she also became awakened to the pleasure she felt fighting completely naked. In that moment, a new warrior was born—donning a mask and charging into battle in her striptease outfit. Vowing to stand against Raziel, Maria declares herself Masked Sister Maria, the guardian of the holy relics!