One thing that really left me scratching my head in Shenmue 3 was the need for two gangs as antagonists. I wouldn't have known that the red snakes/blue spiders were two separate organisations until I learned it in the dlc. I always assumed that Yanglang was a sub-boss in the red snakes and muscles was the head honcho. The supposed conflict between the gangs was never explored and it makes you wonder if Yu intended to flesh this out more but due to restraints, couldn't fit it in.
If I had to piece things together, I'd say that Niao Sun (who seemingly has influence over the gangs in Guilin), pitted the red snakes and blue spiders against each other to kidnap Yuan and the other stone makers in order to earn her favour. The Red Snakes swooped in first, were a little more competent and got their men, while the blue snakes were left with the crumbs. The thing I find really interesting, and it was never expanded on, was that Niao Sun was very close to Shenhua and Ryo's whereabouts from as early as the Bailu village chapter. There's a reason why she boarded the same boat as them to Niawou and it wasn't a coincidence. If her role in this game was fleshed out more, the story would have been way more satisfying. The pieces are there, they were just never used.