Furry art is not very popular in japan, but believe me, there's a LOT of japanese furry erotica (mostly doujins), albeit only a fraction of it is translated. What also happens is that some westerns sites like nhentai don't upload much furry stuff overall. However, you can always check e-hentai or exhentai to see the amount of furry doujins they have. (Or search furry in pixiv).Interesting, you don't see full on furry content much in japanese erotica.(from the very limited amount I have seen)
Also, is good to note that all the artists in this game are well-known japanese furry artists.