Does anyone know what stories are the credits background illustrations from?

If you mean the last two pages, the first one looks suspiciously like "19 days" art though its probably not 19 days. The other one looks a lot like Shen Sheng. I´m probably wrong though.

The "19 days" art is actually from another book the author did called "mosspaca advertising" and it doesn't revolve around them, but their storiesare in there

Thank youヾ(❀╹◡╹)ﾉ~