Most1 Kodokan judo techniques are named in a somewhat systematised way, describing the major visual/mechanical components of the technique (e.g. koshi-guruma "hip wheel", o-soto-gari "major outer reap"). This is in contrast to the various impressionistic names of apocryphal techniques (e.g. jigoku-jime, chōchin-datami, tama-guruma).3
Yama-arashi (山嵐, "mountain storm") then seems something of an obtuse anomaly in the Kodokan syllabus.2
What is the etymology behind Yama-arashi?
Does it have anything to do with porcupines (also called yama-arashi, ヤマアラシ, 山荒 in Japanese)?
1. There are other more metaphorical, yet still penetrable, names: tawara-gaeshi, tomoe-nage, kani-basami, tani-otoshi, kesa-gatame.
2. Along with a couple of others: tsubame-gaeshi, kawazu-gake.
3. With some being named for famous practitioners: tengu-nage, nanma-otoshi