I strongly assume that there was originally more zôgan on this one. The aesthetical concept of
this interpretation was already introcuded by the Ko-Shôami group. It is based on a contrast of
round (the shape of the tsuba), angular (the masume), and round (the tsuka/saya) when worn.
This concept got later a lyrical name when adopted by the Higo artists, namely "sugimori-hôen"
(杉森方円), meaning about "cedar forst in an square" (see pic below). Otherwise it is just called
"masume" (枡目), "measure" or "square".
Or take a look at this link, a nice example for a typical Higo-koshirae:
http://www.choshuya.co.jp/sale/sword/10 ... nemoto.htm