Being Sacrificed by the School Belle at the Beginning? I Wake up and Kill the God with My Backhand

At the school celebration, my girlfriend, the school belle, pushed me towards the mutated giant beast in public. "You're just an ordinary person anyway, die for me!" The moment blood spurted out, the world's first God-killing system was suddenly activated. I tore the giant beast into pieces with my bare hands, and walked towards her who was paralyzed with fear, covered in blood. "You're right, ordinary people do deserve to die." "But now, it's your turn."