So the question is, how could one plausibly achieve this institutional change?
Hendryk,
The IJN was supposedly the less xenophobic and more "worldly" branch of the Japanese military. I think if the attempt began early enough it could succeed.
Was Germany in a position to provide training for foreign submarine officers before the signing of the Anglo-German Naval Agreement?
After WW1 and in order to get around the restrictions of Versailles,
Weimer Germany built and tested submarines in Holland, Sweden, and Spain along with building and testing tanks and armor doctrine in the USSR. Germany apparently had no qualms about sharing technology and doctrinal experiments with former enemies in return for freedom to research the same away from the eyes on the Versailles guarantors.
While distant, Japan would have been a nicely quiet location for similar projects because the Japanese were creating their own veil of secrecy over military matters.
IJN thinking was tantalizingly close to wolfpack methods seen in the Atlantic. Japanese subs were already supposed to work together, in conjunction with scouting aircraft, and under the direction of a command submarine. If the focus on warship attrition prior to a theoretical battleline clash could be muted, a commerce destruction campaign might possible.
The US had dropped Orange by the mid-30s and Japan knew it, but Japan kept planning on the US following that plan more out of inertia than anything else. She actually built specific units for her navy and chose which capabilities they would possess with an eye towards defeating Orange. The result was that the IJN became a very specialized entity which fared rather badly in the actual war.
If the Germans could get across the point that no battle plan survives contact with the enemy, Japan's thinking, planning, and execution would be more flexible.
Also, as I've noted, Japan's overall submarine commanders will need to develop the ruthlessness shown by their OTL US and German counterparts. Both those nations realized early on that poorly performing sub skippers needed to be removed from command earlier, not later, and that aggressive prospective commanders needed to be promoted ahead of their fellows. Japan kept poor commanders aboard her submarines far too long, allowing them to make tours of peacetime length regardless of their actual performance. IJN subs cruised the shipping rich waters of the US West Coast, the Solomons, the Philippines, and the Indian Ocean while logging either "no traffic" or "target too far away" comments. Doenitz and Lakewood would have yanked those commanders in a New York second after such reports.
Bill