Lofi hip hop genre refers mainly to the quality of the sound, rather than a genre. It stands for Low Fidelity. Some consider it as a subset of chillhop music. Typical sounds and samples in the genre include clipping, tape noise, a sort of nostalgic, naturally dusty/gritty sound. The general opinion behind the Japanese influence on lofi hop hop music is that many lofi hiphop producers are fans of anime. That led to them to using using screenshots and video clips from their favorite/most nostalgic animes as album/song art.
Pioneers and key/main artists in the genre include J Dilla, Nujabes, Samiyam, MF Doom, madlib, samiyam, 9th wonder, CULP, Dibia$e, TEAM CANADUH and others.
Nowadays, the genre is experiencing a growing popularity with a lot of new producers releasing pretty amazing beats. Also, growing communities like Reddits r/LofiHipHop and various YouTube channels are fostering a great culture to cultivate the genre.