Japanese city names: Kyoto > Osaka > Tokyo > Satsuma
Note, if Toku founded a city after we met him, there should be a BUFFY log entry that Tokugawa has founded Tokyo in a distant land. Whether we can see it or not. Nobody has said they saw such a notice (though maybe its there and we overlooked it). So yes, I am basing my bloodlust on the idea that Toku has only two cities and even if we only take Osaka it cuts in half his ability to cause nuisance. Also, when we had diplomatic contact with him the city names are either red or white, whether we know where they are or not. There should be no need for guesswork here on this point. (As a reminder, contact Babylonia and count how many cities they have - note that the capitol is never listed as it is not tradable).
Why do you think he has four?
In any case, I feel
pretty strongly that winning wars is better than losing them (or stalemating). We can get Osaka... it will cost probably three or four dead axes. But thats pretty cheap for what it gives us (unfettered access to corn, secure border and weakling neighbor).
What to do with Osaka? I think we should take our time and think about that. We can hold it, by loading up with defenders and start making culture there. Infecting it with Hinduism is a good idea. But we could wait and hope for free spread from Xtian or Hindu holy cities (save a Xtian missionary). We have no contact with the Bhudist holy city so we cannot get spontaneous Bhudism spread. Note: One more argument for exploration.
Another option is to give it back, or allow it to flip back. I'm with Deckhand on not liking that idea -- if we KNEW we wanted a religious VC I'd see the benefits, but culture is still the main VC... so keeping it makes more sense.
I think it might be a mistake to start focusing on the culture growing aspect of the game just yet. Fast Culture VC's usually start like any other game: tech to military advantage, whack a neighbor for land and developed cities and weakening the opposition. Getting more religions is usually not an issue if you are the meanest SOB on the block.
I agree that Catapults are needed for total victory. So we should take Osaka, and hold it while we tech construction (instead of CoL). We could still lose the Confu race even if we proceed with CoL plans, but with Cats we are 100% assured of gaining Bhudism. And making a safe eastern border, allowing us to focus on the western front. All's quiet on the western front, but that won't last. Who wants to have to keep two stacks?
Note, another option that nobody has mentioned is to tech alphabet, make a spy, and start a revolt in Kyoto instead of using seige. But Cats are probably more conventional and trustworthy. But a spy would be faster and alpha is more in line with other techs we want (Literature).
I'm guessing that how we handle this present opportunity/dilemma will be a difference of at least 30 turns in finish date. And that is from my truly scientific process of just pulling a number out of my backside.