I'm not sure if this is Japan's largest floating crane or if it's the biggest in the world, but either way, it's huge!
The "Yoshida" was built by Mitsubishi Heavy Industries Division has a boom length of 132m and a lifting capacity of 3,700 tons. Each hook is 10m tall and it's operator needs to climb 800 steps to reach the small cab atop the crane. http://www.iftk.com.br/wordpress/huge-floating-crane-lifts-bridges-and-submarines/
Why shouldn't the Japanese Self-Defense forces own submarines? Aren't they allowed to defend their nation from other peoples' armed forces?
I can't figure out what class of sub it is. This is a list of what Japan has currently.