I do think Usamaru Furuya is pretty popular about 6-7 years ago in the "niche" category of the manga world (though not as gore as Shintaro Kago), as you can see many mangas of him got translated here and there, just that his work collection is pretty big and he works non-stop so it keeps building up. If I have to said Furuya’s style is something between Junjo Itou and Shintaro Kago: can be scary, guro at times but with strong romance aethestic, and the unque weirdness (up to straight out silliness) you would with Japanese authors as well.