When reading longer lists of Japanese names — for example, in closing credits or attendance registers — I always have two rather contradictory impressions. On the one hand, there are a handful of very common surnames that seem to be around just everywhere. But on the other hand, you are always sure to find a name or two you feel you've never seen — let alone pronounced — before.

Incongruous as this may seem, both impressions have a pinch of truth to them. But, to start with, how many Japanese surnames are there anyway? This is a rather tricky question, because the total number of names crucially depends on how we decide to count them.

A first problem in this respect are surnames that sound the same but use different kanji characters. Take names with kawa (river), for instance, which can be written either 川 or 河. Accordingly, there is 川原 and 河原 for Kawahara, 川村 and 河村 for Kawamura and so forth.