I apologise for the delay, but these took some doing and a lot of the detail work was a real pain.
The short version: Musashi won and Kojiro ended up dead. On the plus side, he got an island named after him — “Ganryu” was a nickname of his.
How exactly the duel played out is debated, and it’s been suggested that the story of the duel itself was only created later to cover up for the fact that Musashi just went and murdered Kojiro.
That being said, certain famous details, true or not, have been immortalised in re-tellings of the story.
Most famously, that Musashi carved a wooden sword out of an oar for the duel (possibly in order to have a weapon with more reach than Kojiro’s sword — nicknamed the “laundry pole” due to the length of its blade). That’s why Musashi’s sword is brown and doesn’t have a guard in the picture.
Other elements of the story include the fact that Musashi deliberately arrived several hours late, due to some combination of attempting to unnerve Kojiro, having the setting sun (seen at the left of the picture) at his back to blind Kojiro, or being able to immediately retreat from Kojiro’s supporters with the changing tide.
To conclude with the bit of trivia: in the English dub of Pokémon, Team Rocket are Jessie and James, after famous Old West outlaw Jesse James. In the original Japanese, Jessie is Musashi and James is Kojiro, after the combatants from Ganryu-jima.
This one didn’t go so hot…
First things first, that’s not his face.
That’s a mask, so that’s supposed to be metal rather than skin (and that’s why it’s grey). If you zoom in close enough, you can see his skin through the eyes and mouth of the mask.
Secondly, the thing he’s holding is a signalling fan, a reference to the famous incident at the fourth Battle of Kawanakajima where Shingen was ambushed by rival warlord Uesugi Kenshin and had no means to defend himself but his signalling fan.
Historically, Shingen was one of the most powerful warlords of the late 16th century, controlling a large territory in east-central Japan based around the modern Yamanashi Prefecture. His campaigns culminated in a push west to drive Oda Nobunaga out of Kyoto and seize control of the capital. Ultimately, he died while laying siege to Noda castle under unclear circumstances.
The most common theories are that he was either shot during the siege or died due to lingering wounds or illness, possibly a particularly unfortunate combination of both.
Without Shingen’s leadership, the Takeda would suffer several disastrous defeats at the hands of the Oda. Members and branches of the clan would survive, but the Takeda were effectively wiped out as an independent political or military power.
Incidentally, the death of Shingen and the downfall of the Takeda is the basis for my favourite Kurosawa movie: Kagemusha, about a body double hired by the Takeda to make their rival clans think Shingen is still alive. Suffice it to say, it doesn’t work out and everybody dies.
Also, Nobunaga appears as the major antagonist wearing what can only be described as an awesome Dracula cape.