If you sought kanji with which to make gender distinctions, what
would you use? My mind would naturally go to these two: 男 (54:
male, man) 女 (35: female, woman) These characters can indeed
serve that purpose, but they don't always mean what you might
think. Moreover, some other pairs of kanji also distinguish male
from female. Let's start by looking more closely at 男 and 女.
These can represent size differences. According to Dr. Gabi
Greve, a longtime Japan resident and creator of the Daruma
Museum, male-female size designations apply to twin mountain
peaks. People call the larger one 男体山 (なんたいさん) and the smaller
one 女体山 (にょたいさん). Clearly, they're not identical twins! One
finds an example of this on Mount Tsukuba. However, 男体山 and 女体山
are not always paired. There are several instances of 男体山 with
no 女体山 in sight. Twin waterfalls also attain 男- and 女-
designations. Essay 1550 on waterfalls (滝) presents these terms:
男滝 (おだき: greater waterfall (of the two)) male + waterfall 女滝
(めだき: smaller waterfall (of the two)