Why does Nissan have 3 sports models for JDM?

Silvia, Skyline, and Z. All were different models and have been produced along side each other for their entire lives. Yeah, Japan has a huge car culture, sweet, but then why is Nissan the only company to do so? The 300zx, S13, and R32/33 were all concurrently available as 4 seaters, so there's no coupe appeal reasoning. Was there a huge difference in price? I'm just confused about the huge opportunity for sales cannibalization, even though it seems to have never been an issue.