Seiki and Matsuyuki, two sisters born out of hope and love, carry out an important mission that was entrusted to them: Vanquish the darkness that has plagued the virtual/accelerated world for many years, and usher in a new era of harmony, a 'hidden haven' where people wouldn't have to hate each other, but instead have joy and fun together.

And his first one with his beloved senpai. (Set after the events of Volume 4).