While beautiful, most of these pieces are primarily ceremonial or intended for generals who would rarely involve themselves on the battlefield†.<p>Almost all of these pieces date from after the unification of Japan under the Tokugawa shogunate (c. 1600). From 1600 to 1850 Japan experienced a stable period marked by very little real armed conflict. During this time, the samurai transitioned from soldiers to what were effectively mid-level bureaucrats. However, unlike most bureaucrats, they managed to retain all of the trappings of a martial lifestyle, including ornate armor, beautiful swords, and the occasional mortal duel. It was during this time of relative peace that these (sometimes ridiculous) fashion pieces developed, somewhat complicated by the tradition of incorporating pieces of much, much older helmets into the "core" of the helmets (one of the helmets in the OP has a core dating from the 14th century, but was significantly embellished later on).<p>†This is generally true of what arms and armor have survived from around the world. The stuff that was actually used rusted away long ago; the highest chance for survival was to have been so valuable that no one dared to actually take it onto a battlefield.
I highly recommend checking out the Samurai Collection[1] referenced here, if you can get to one of its showings – it travels around quite regularly. The exhibit is great, both in size (good, but not overwhelming) and presentation details. Especially the full (O-yoroi) armor, which is in transparent cases that let you get up close on all sides to see how the armor is constructed, and the many levels of artisanship that go into each piece.<p>Also, the exhibition venues will often do things like find local artisans to demonstrate related skills. E.g. I demoed making the armor lacing braids (as much as 200-400 yards, in reeled silk, per suit!) when the show was at the Portland Art Museum.<p>[1] <a href="http://samuraicollection.org/aboutus_history.html" rel="nofollow">http://samuraicollection.org/aboutus_history.html</a>
After looking at pictures of a bunch of samurai helmets, I came to a realization that Darth Vader's helmet is more or less the shape of a samurai helmet. Maybe this should have been obvious to me (especially being a fan of the Hidden Fortress film), but it was a cool discovery for me.
Is the fantastic impracticality of these helmets due to the handicap principal ( <a href="https://en.m.wikipedia.org/wiki/Handicap_principle" rel="nofollow">https://en.m.wikipedia.org/wiki/Handicap_principle</a> )?
If anyone lives in London and would like to investigate how the ancient sword arts of japan tie into meditation, I highly recommend <a href="http://battodo-fudokan.co.uk/" rel="nofollow">http://battodo-fudokan.co.uk/</a>
There's an interesting helmet with a large statue of Fudo Myo-o, the "immovable radiant king" of Shingon Buddhism.<p>I don't recall seeing another helmet with a full statue. Are there more examples?