Alright, updates from the Japan front.
I somehow punched back down through the infamy limit from a lucky ruler death and the resulting bonus legitimacy (heir with good claim's all it takes), still sitting on terrible relations with the entire known world and 17% inflation, only to have the Mingblob, who are eating into Indochina as usual, get a mission to Conquer Taiwan. Which is Japanese-colonized and popped Chinaware, so I am NOT ceding that. But they try me anyway.
My fleet is still crap compared to the gazillion of galleys they have, unfortunately, and I lose all of my transports and galleys in the naval battle. Ming crosses the new narrow strait to Taiwan and sieges it. On the northern front, Joseon is getting stomped by Qing. So, what does one do? Ming, would you like Joseon to cede four of its provinces to Qing, giving you nothing but infamy and leaving Taiwan in the hands of Japan?
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They would accept this offer.
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Dissolved alliance with rump-Joseon (still owns Xia and three Indochinese provinces, but they have dreadful AE) afterwards, because I had a mission to fulfill.
Fast forward four years and one huge fleet building program later, I myself decide to press my "Get a piece of Korea" mission. Declare war on Joseon?
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They are in Ming's sphere of influence. Ming is defender of the Confucian faith, and will protect them. Ming is allied to Qing. Ming is at war with Golden Horde and a boatload of minors/hordes. You will get a stability hit for the Royal Marriage.
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Whatever. Conquest casus belli, gogogo! Ming has honored its alliance. Ming is now the warleader.
Ming has made peace with useless enemy! x10 They have sent some forces to Korea.
Japan has occupied the Korean mainlands! The Ming forces were crushed! (Where is the entire army? Only 20k arrived?) The Ming navy is beaten! (But still attempts things)
Qing has honored its alliance with Ming! Qing is tossing men at Korea! Qing's navy is foolishly exiting the ports! Qing's army feels the wrath of the Quality slider and Shock Six generals!
Joseon does not want to cede all three of the required provinces! Japan blockades their Indochinese ports. Joseon agrees to ceding the three provinces!
Mission complete. Get new mission. Occupy Nanjing! Cancel mission.
White Peace with Qing, 25 ducats for Ming to shut them up.
I just fought what amounts to all of mainland Asia, and won. Not even westernised, or close to it. Fuck yeah. So much for the AI being smart...