Forced to Change Profession as a Magical Girl

What's it like to take the wrong sister's schoolbag? Thanks for the invitation. After I took my sister's schoolbag by mistake, I became a magical girl in her place. :). The protagonist is a delinquent boy. After he took the wrong sister's school bag and took out his sister's magic wand during a fight, everything changed! Who would have thought that there really are magical girls in this world? ! Unfortunately, the protagonist becomes a short Loli, while the younger sister becomes King Kong Barbie. As compensation, the protagonist has to trade jobs with his sister. The protagonist's magical girl: Secret Magic Skull Crushing Kill! After returning to his normal status and turning into a delinquent, there was another rumor in the school—— The boss of the delinquents in our school actually likes pink bunnies! Protagonist: "..." This fucking life. Purpose: Use magic to defeat magic