I think Kisame would hate him. I think Kisame would outlast Danzo and his Izanagi. Danzo doesn't really have anything that can harm Kisame, especially if he uses Samehada. Danzo can escape the water dome using Izanagi but that's about it. Kisame would kill his Baku Summoning easily. Kisame stomps easily at close combat so Danzo would be stupid to do that. Even if Danzo can manage to use Izanagi to create an opening, Kisame can heal with Samehada. Kotoamatsukami is the only way Danzo can win and we're not even too sure about how that works yet.