I had an odd thing happen in my current Shimazu campaign. I am at war with two clans on the island you start on. One red and one white, I cannot recall the names. That I can understand. But I was sending two ships to explore the rest of Japan to discover new clans so I could trade and the like with them. Along the way I discoverd Imagawa. A small clan of three provinces far east of me. My enemies are not allies with him, I don't think they trade with him and our only interaction is a small fleet that passed by their coast. A turn or two later, he declared war on me! We don't share borders or anything! I found that odd. Finances are low at the moment and I want to avoid as many conflicts as possible. Bizare. He has no fleets near my small 3 province holdings either. None of my two trade fleets were molested as well.