Nepai was once an obscure kata in the Karate world but over the decades it has become common-place. I find the increase in the number of Nepai Karate kata that you can view on the internet baffling but the main reason I think this was is because Nepai was retained by very few Okinawa Karate styles. The only two that I am aware of were Mabuni Kenwa’s Shito-ryu and Kyoda Juhatsu’s Tou’on-ryu. As the story goes both men learned it from Go Kenki during their involvement in the Karate Study Group. Go Kenki, as we all know, was the Chinese tea merchant and supposed crane boxer who immigrated to Okinawa at the turn of the 20th century. Perhaps other students involved with the Karate Study Group may have been familiar with it, but as far as I know they never passed it down.
Another thing to consider is that Mabuni, who was a prolific author, did not list Nepai in any of his Pre-WWII publications. Nor was it listed in any pre-war book on Karate that I am aware of. Hence information on Nepai was extremely hard to come by even in Japanese. Indeed, I do not know of any mention of Nepai in any Japanese language Karate book until the 1980s. At that time Otsuka Tadahiko and Tokashiki Iken wrote about Nepai in their respective publications. Both men had traveled to Oita prefecture to learn Nepai from Kanzaki Shigekazu the then head of Kyoda’s Tou’on-ryu and I remember Kanzaki sensei telling me about their visits.
Regardless, both men must have seen value in it as they include it to this day in their curricula. With that in mind, below is a video of Nepai from Third Anniversary Memorial Demonstration for Higa Yuchoku conducted by Goju Kensha. Overall I’d say the performer does a good job, but it’s clear the Goju Kensha idiosyncrasies have crept it (I’ve seen the same thing for Gohakuaki rendition). This is inevitable every time a kata is passed down, but this is not a bad thing. The most important point is that the principles of the kata remain intact.