Board Thread:General Discussion/@comment-4698889-20170224092621/@comment-30870488-20170302041838

The Unknown Rin character could also be the Rin in Wordplay. (Whoops, you already said that, sorry)

I looked at the online novel, since Pixiv added a few pages, and I read the back with the characters and the Vocaloid counterparts, as well as the character sheets. The Postman, as Allen, could be like what happened in the Seven Crimes and Punishment story, where Allen is set on a journey to meet the sinners and such by Sickle.

(This probably is a stupid theory, I'm so sorry xD)