Errol, how-on-earth did you manage to reduce your infamy enough to unify Japan and annex Ming, Korea and Manchu by 1473? As far as I am aware, that'd be possible with personal unions, but unifying Japan and defeating both of them before 1423 strikes me as a bit too extreme. In fact, it seems Ming lost territory, but wasn't fully annexed, so a PU is out of question.
I'm playing Death and Taxes. This means I had access to the Nationalism casus belli which is half infamy cost to unify Japan, and could start around 1356 (iirc). I started as Hosokawa, which is the largest Daimyo in D&T (Japan's a lot more divided there) with five provinces, and annexed my way through Japan. I, however, got greedy and got about 20 infamy over the limit in the final push. That was... painful. Ryukyu declared war on me in the aftermath of that shitstorm.
After a lucky ruler death and a huge legitimacy/diplo skill boost, I eventually went under the cap and consolidated. However, before I could build a significant fleet, Ming, who had unified China at this point and started blobbing (faction system appears to be disabled in D&T) got a mission to conquer Taiwan and attacked me. I only got away with all Japanese territories by ceding provinces of my ally Joseon instead, who had been occupied by Jurchen -> Qing. After that, I dissolved the alliance and attacked them myself because I had the "Expand into the Korean Peninsula" mission. Three more provinces. Joseon only had their capital and some holdings in Central China (inheritance) and Vietnam left. I inherited them eventually, even though I never even laid claim to their throne, and released their non-Korean holdings, forming Xia and Dai Viet.
At this point, Ming wanted Taiwan again, but I had a fleet and kept them out while my land army was busy dealing with Qing. I won because my enemies failed to cooperate, got Ming to release Fang and secured the rest of the Korean peninsula.
The next war was the fault of Qing's, but they pulled in Ming and Fang regardless. Same procedure, I won, Qing lost more coastal provinces. At this point I had already started to colonize east Russia. After the truce was over, I figured that Qing was going to keep declaring anyway and so attacked myself to get a better CB. Won, expanded my holdings in Manchuria and a bit further down the coast. Wu was force-released somewhere around this point and Ming lost a mission-critical province as well. I thought that was the last of them, but I underestimated their stubbornness. Unfortunately, Ming did not join the second Qing reconquest of rightfully Japanese territory (ahem), so they lost more land, including Beijing, were forced to release Oirat Horde and Fang (who did join) went Shinto and got some Chinese minors split off. Only then, finally, Qing shut up.
But Ming did not. However, they declared with Chinese Unification, which is a damn fine CB for expanding into China (as my mission wanted me to do anyway), so I curb-stomped them, force-vassalized Qing and got Ming to cede four provinces on the northern Chinese coast and to release yet another Chinese minor. And because the Ming army was defeated, other nations sensed their opportunities and tore chunks off Ming themselves, leaving what you see in the map - a sorry mess.
As you see, everything went through legally although I went over the limit once (and never again, god, that shit hurts). In fact, I didn't even start most of the wars and therefore got quite a few provinces for 3 or 4 infamy - although Cleansing of Heresy and Conquest were also involved.