Anyone know the chapters in the original to read for backstory?

Pilsang comes up alot in the main story right from the beginning so I'd suggest just reading the main story, the Chairman doesn't really come in till around chapter 40ish

chairman is shown in chapter 36 I believe, he's not really in alot of the chapters though

the prologue chapter basically sums up their interactions from the main story thought so you should be fine not reading their chapters from the main story.