Shimazu is a one-province minor daimyo in Southern Kyushu (Western Japan) and the closest daimyo to Ryukyu. Their ideas are mainly focused on the military, which grants them the nickname 'the Prussia of Japan'.
In 1444 Shimazu starts as a weak isolated Daimyo, however its two neighbors are even weaker and Shimazu also has a reconquest cb on one.
The player should try and declare preferably on its reconquest target on 11 december 1444. After building up to 3 soldiers, the war should be a whim.
After the initial wars the player should seek to keep 2 troops above his forcelimit to overwhelm and stackwipe neighbors.
Building galleys is vital in conquering the larger nations on the other island. When reaching too much AE the Shogun might declare on you, however after you have conquered a large part of japan, the player will have a considerable amount of army tradition, and prestige. Your quality of troops should be more than enough to win against the Shogun by selectivly fighting small daimyo armies and destroying them. After this war Japan is your play ground. You could decide to become Shogun, or continue you conquer spree.