This is about an author on a quest to write a masterpiece, which revolves around mining some secrets contained in the red leather chest of his dead father.

This sounds grim and has some autobiographical context. But it is actually quite fun at this point, especially with the theater group(ies) who are trying to adapt the author's work in an authentic way (and also the work of other famous Japanese novelists).

I find the interactions between the theater group and the author hilarious because the author giving them access seems to validate his work in this weird social contract between artist and audience. They're trying to prove that they are serious and have ironed out the difficulties in adapting his work and he is feeding them material -- but probably doesn't need this amount of effort as I think he quite enjoys the attention.