The premise of this "Welcome Back, Mr. McDonald" reminded me a bit of the American movie "Noises Off" (1992), with Michael Caine and Cristopher Reeve. And indeed both are adapted from a play, and both portray the crazily funny misadventures of a troupe. Whereas that one was written from the point of view of a director, though, this one is actually done from that of a writer. And as anyone who's ever tried writing professionally will be able to confirm, it is surely based on the many frustrations and troubles writers have to go through (unbeknownst to the vast public, the final version of a script has often little to do with its first draft; some of the changes have sound reasons - like budget restrictions, for example! - but it might often happen that retouches are actually caused by frivulous motivations - a long list of which is funnily depicted here! ^__^)
Just like that other movie, though, this one as well suffers from some silliness and some exaggerations...so the script is very good but not perfect.
The cast is great, and refreshingly so imho due to the absence of high-school-aged idols, LOL (particular mentions for the always great Toda Keiko and Nishimura Masahiko!)