Minamoto, always war mod.
Why haven't I formed Japan? Because I took over Kyoto and destroyed the Shogunate (I HAD NO CHOICE). But whatever, I like Minamoto's color more anyway
So I went in these steps:
War with Japan happens, auto-annex japan
War with Taira, after a while they were gone
Wars with Fujiwara, took over north Japan
War with Tachibana, took south japan
at this point I looked at Okinawa and ended Fujiwara
took Korea from Ryukyu
Took over Manchu, took over Korea
more Ryukyu taken
Things that are not too special:
Holland is the only HRE member left
Oirats. I am at constant stalemate with them.
Ryukyu, you know, was actually successful, then I came to Korea.
Taungu. OMG.
(Also, I admit that I cheated, on account of not succeeding without them)