My Grandpa Is Actually a Magical Girl?

"My grandfather's hobby after retirement was to be a magical girl, until I stabbed the beast's den at school." Other people's grandfathers: play chess, walk the birds, maintain health and make tea. My grandpa: pink twin tails, lace miniskirt, patrolling the streets at midnight with a hammer bigger than a man. Heirlooms from other people's families: jade bracelets, antique calligraphy and paintings. My family heirloom: a shoddy plastic shapeshifter stolen from the attic. Wu Yu always felt that his grandfather was just a bit addicted to cosplay. Until the whole school was besieged by the beasts and there was no hope of rescue. He held the broken plastic and heard the screams of his classmates and the nagging of his grandfather: "Real things are driven by wishes, you copycat... Tsk, but what if something happens?" So, he yelled out that shameful line—— "Transform!"