Japan have been known to have weird fixations, but, then again, they’ve always been up there in terms of the world’s trendsetters. So when word gets out that they’re become obsessed with hamster butts, we’re bamboozled.

The Japanese have even created their own word for a hamster butt: “Hamuketsu”, combining the Japanese words for “hamster” and “butt”. (Of course.) They’ve got books of butts. So far they’ve sold 40,000 copies of two books filled with images of the fuzzy behind, with the third being released at the end of the month. Who would’ve thought there was so many varieties of hamster butts? Oh, but just like human butts, hamster butts come in all shapes and sizes. They also prefer the male butt as it’s larger and rounder.

A representative from one of the publishing companies reveals the appeal, saying “The great thing about hamuketsu is that it is delightfully cute. I can’t stop smiling when I see these butts.” They even have a Facebook page dedicated to hamster butts, so be sure to check it out before you rush out and buy the book.