On school break, Marinette heads to Shanghai to meet Adrien. But after arriving, Marinette loses all her stuff, including the Miraculous that allows her to turn into Ladybug!

In 2046, many aspects of life are carried out on a virtual network. No matter how advanced the time becomes, however, bullying never disappears. Haruyuki is one of the bullied students. However, one day he is contacted by Kuroyukihime, the most famous person in the school. “Wouldn’t you like to ‘accelerate’ and go further ahead, boy?” Haruyuki is introduced to the “Accel World” and decides to fight as Kuroyukihime’s knight.