User blog comment:B214/Question and Answers/@comment-173.173.85.57-20130723010154/@comment-1359322-20130723031601

It's still not compiled into a Volume so you won't be able to read it unless someone translate it for you.

Well a summary of the story is that Saji got infected by a disease called the Dragon Flu and Sona decides to borrow Issei temporarily.