And the Oda could always pirate a European style ship to copy, make it disappear to a remote island such as Sado, disperse the crew so that they could learn Japanese and their brains could be picked and go from there. And send emissaries--spies--to European courts. Spain's and Portugals, if none else are available. And make sailors who appear to speak different langauages than Portuguese disappear. Anything for a different and unbiased perspective on Europe.
(Yes, I got the idea from James Clavell's Shogun. Toranaga to Anjin-san, parahrasing the Borg" You will be assimilated. Resistance is futile!"

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European style ships are very valuable for Oda Nobunaga, as you have pointed out. Because they are the answer to Japan's isolation. And because properly trained to man them, they can carry Nobunaga's samurai to the lands of the majority of Japan's daimyo without passing through the territory of other daimyo. That is revolutionary. In fact, that could very well be the POD that enables Oda Nobunaga to unify Japan, and go on to reward Daimyo with territory in places such as the Ryukyu Islands, Taiwan and Ezo and then maybe Tondo before the Spanish even get there. If the Spanish can conquer Lapu-Lapu, Oda Nobunaga surely can.
In doing this, Oda Nobunaga is modifying Japan's bushido tradition into a naval tradition, similar to Great Britain's Royal Navy. As ships become Japan's weapons of war, ships become part of Japan's weapons of the warrior. And seamanship and gunnery (and for the time being, archery --and rocketry, which the Japanese know from the Chinese and which can set enemy vessels rigging and powder afire from a distance ), part of bushido. The big difference is that ships must be crewed
cooperatively . A ships crew must fight as a unit or all die when the ship sinks be the enemy human, the weather or hunger, thirst or scurvy.
I think this is one of those cases in which one thing follows upon another without the man initiating the changes, (in this case Oda Nobunaga) being aware of where this is all leading.