Accelerator never expected to find Kana Hanje standing at his front door today. Years had passed since that fateful day in the playground where Accelerator's Esper ability had been demonstrated with extreme force. Kana was forced to leave Academy City after the incident, but she never forgot the boy that had defended her that day.

Now, in the present, she returns to find that an 18-year-old Accelerator has put his quest for power behind him and is living a quiet life with his ward Last Order. His dark and violent past prevents him from letting anybody get too close. Summoning all her courage, Kana confesses her true feelings for him. Moved by her words, Accelerator gives in to his own desires and the two begin a journey of new experiences and emotions. But Kana isn't the only person from Accelerator's past that has come back to Academy City to confront him...