On what would typically be another ordinary day, Lala Satalin Deviluke takes one of her recent inventions—a robotic cat with cloning powers—to school for a chance to show it to Rito Yuuki. Upon accidentally touching the gadget, Rito begins repeatedly duplicating himself, and the school is soon entirely overrun by a horde of his clones.

The only way to deactivate the cat is to hold its tail; however, its agility makes this a challenge. Will Rito's army of himself be able to catch it, or will the Earth be flooded by an unstoppable wave of duplicates?