Things have been easy since the battle against Himushi and Magatori, so much so that Osamu and the gang can barely figure out what to do with themselves. Of course, the peace never lasts.

One day, a young girl named Rousoku Himawari, Osamu's ex-girlfriend of seven years, shows up on his doorstep completely out of the blue. She doesn't remember how she got there, nor does she remember anything about the past seven years of her life. Osamu contacts Lucrezia, Shinju, and Cyanide for their help on the matter, suspecting that Rousoku's memory loss isn't medical, but supernatural.

In trying to find the root cause behind Rousoku's seven year gap in memory, Osamu and the others discover a gruesome and horrifying truth about Rousoku. She didn't forget what had happened in the past seven years —she died seven years ago and has come back as a ghost, unable to move on to the hereafter.

On a time limit, Osamu must work with Rousoku to help her pass on properly, but doing so will require the both of them to confess heartbreaking truths about their failed relationship, be honest about their divergent wants, and confront the devastating pain they both inflicted upon each other seven years ago.

[Sixth book in the series]