Bump. I'm in 1940 in my Japan game, 1900 start, and never once got an event to let me take over Korea. Nor have I gotten any events to take over the Dutch East Indies even though I took all of French Indochina (Vietnam) early in the game. The only neutral invasion events I've gotten were for some of the smaller Pacific islands and even those I only had a 1/3 success with despite being the largest power in the West Pacific. I finally called BS on the game and edited my save file to give me ownership of Korea.
Please add more events or increase the likelihood of events for Japan to invade places like Korea and Indonesia to reflect its expansionist nature. Or give them an ability that lets them invade neutral locations if they're in the same region as a major power they're already at war with. For example, If at war with Russia you can invade Korea, and if you're at war with England or the USA you can invade Java.