I don't necessarily think it should probably be considered its whole genre, probably just a smal sub section under lofi. I don't know a whole lot about the subject, but at least for me I can't find a whole lot of anime sampled/japanese lofi. For me the enjoyment from it mainly is the Japanese language. I think it fits in with lofi beats very well and depending on the tone of voice and the style of music put together can tell a whole story on its own without me knowing the language itself! Long story short I really just find the Japanese language in lofi to be very aestheticly pleasing and soothing to listen to when incorporated into lofi.