Well, Hibiki is his favorite character with HibiIna being his favorite pairing. But it's just he also likes drawing some sad stories as he stated on Facebook.
I like how this worked out. Happy stories and endings are great and all, but I do think there needs to be more stories that go into survivor's remorse. As sad as it is, this ending feels more real to Hibiki's history and character.
"Alrite procrastination time is over. I'll just read one last story.... Oh yay a cute story to get my spirits up before I start my homework [and continue at it until the end of the next month]!"