I was first exposed to Japanese erotica/porn from a personal collector of VHS tapes around 25 years ago. I remember that he called the genre “Nampa”. In his list of videos for sale and rent were strip wrestling, strip games and TV shows, women being stripped and humiliated by gangs of men, etc. It was definitely eye opening compared to straight-forward American porn. Back in the day, I paid good money just to experience a few of these videos. For rentals, I made copies by hooking up two VCRs, even though the quality was poor.
As the internet matured, Japanese porn became more readily available first on paid sites, and now on free sites. It always seemed strange to me that edgy topics like simulated assault/rape is more common in Japanese porn compared to American, but genitals are conservatively pixelated in Japan. I guess the Japanese are more liberal on some aspects of porn but less on others. Nevertheless, it seems the craziness of Japanese porn peaked around 2010-15, at least based on sites available in the US. The newer titles are becoming less situationally arousing, with more just straight-forward sex like American porn.