Side note, archers did use shields in europe, and so did crossbowmen, though sometimes they were very small and supported by a simple cord. The shields archers had effectively made them very small emplacements, so they could restring in relative safety, they would also usually have a serf (or something like that) in tow, to carry their shield and arrows.
the Pavise
and the smaller shield I can't seem to find at the moment, but spearmen also used them.
Europe, yes, but Japan, not so much.
In the Pre-Samurai era, there was some shield use in Japan, but it died out fairly early.
The Japanese arsenal heavily favored two-handed weapons, and survival wasn't necessarily as a high priority as you might think.
A Samurai, as a mounted archer and two-handed swordsman (who steered with their knees, by the way, not with the reigns in their off-hand, as has been suggested), wouldn't have a use for a shield, and wouldn't have been caught dead cowering behind one, anyway.
Blades for use while mounted would have been the Tachi, or Odachi / Nodachi. In later periods, as Samurai moved away from the traditional mounted combat, they transitioned to the katana, which was worn edge-upward through the belt (not suitable for mounted warfare, but better for quick-draw Iai-jutsu action and CQB).
Infantry favored polearms (gotta love those naginatas).
What shields they did have mostly consisted of tower shields, I believe, for levy infantry to hunker behind when necessary. (Honor-less peasants!)
Oh, and the Ninja sometimes used bucklers. (Pesky Ninja!)
-Jn-
Ifriti Sophist