T'was 300 Years....
Your book now takes place three hundred years in the future (the year 2319). In what ways has the narrative changed? Art and dialogue has a really big impact when it comes to the making of manga. Considering those two factors, inside jokes and information told in the book will become outdated 300 years later. However, it seems rigor mortis is indeed a thing that happens in the body hours after death. Just takes research to confirm possible truths residing in the story.