Bringing a 150 lbs (68 kg) Leonberger dog to Japan

Hello collective! I will be retiring to Japan from California with my Japanese wife in a couple years. There's a problem… we have a 150 lbs (68 kg) Leonberger dog that we need to bring with us. We absolutely will NOT be packing this magnificent creature in a crate and stuffing him into the cargo hold of a plane. No, no and no. So…

I suppose my question is in two parts: First — Are there any airlines that would allow a dog this large in the cabin (we would buy an extra seat for him in first class of course)? Would that even be legal? Or second — Are there any cruise ships from Los Angeles that end up in Tokyo that allow pets aboard? And if so, where in Japan would we disembark to bring him through import inspection? Has anyone gone through this process before with such a large dog (think Great Dane size)?

It's distressing. Please help.

by TheRealElektro