To all of the naysayers who claimed that this clan is no good… you should go back to playing Purple and Green where you're the strategy is simpler and where thinking is not a real necessity.
Imagawa starts off split with decent koku producing provinces so they have several strategies that they can explore.
With your eastern force attack Oda (Gold) almost immediately, because if you don't Oda will.
- Owari is a very koku rich, one-bridge province. Like all bridge territories it is tough to take, especially if the attack-minded Oda is allowed to build up forces here. This was the first province that I attacked.
- From there I took out Mino, which has two areas of high ground overlooking a valley. This is another area that is tough to take and easy to defend but Oda's Ashigaru should be no match for your Samurai.
- At this point you can hold these two areas and Oda should not be able to penetrate, slowly push him back.
- While attacking Oda try to make peace with Uesugi (Blue) and Takeda (Black). Takeda will most likely attack you anyway so go to Uesugi first with your emissary. Either way, I suggest you take up defensive positions on your western front against both clans and wait for Hojo.
On your western front build a spear or archer dojo in one of your three starting countries so you can supply troops here separately. This way you don't have to rely on your capital city (Totomi) and ports to transport forces over.
- Shimazu (Green) will most likely start off making peace with you even though he has you surrounded and outnumbered. Build up forces here for several years and don't garrison any troops in the port city (Hizen) since it cannot be attacked unless one of the other two provinces fall.
- Once you build up enough forces split the Shimazu forces in half by attacking Bungo and Hizo. If you're fortunate enough they will try to take your one-bridge province of Chikugo and then when they retreat you can take Bungo and Hizo almost at the same time. If they don't attack, take out whichever city looks most vulnerable first.
- After splitting these forces tighten the screws on green and simply divide and conquer the entire island. Do not allow the Mori clan (Red) or Takeda (Black) to take a single country or you will have to defend multiple areas instead of one.
- After you conquer Shimazu, defend the Northeast corner from Mori or Takeda and take over the "Australian looking" island occupied by Ronin mostly. By this time your forces should sandwich Oda and you can concentrate on Mori, and Hojo most likely. At least you'll have the koku to be competitive.