[tommasi]

It seems like there are several cruises available from the UK to Japan.

You have to stop at other countries as well and you would probably have very limited time in Japan.

My suggestion is to contact exclusive travel agencies which offer cruises all over the world.

Or, take some short trips to nearby European cities so your b/f can feel more comfortable about flying and then come to Japan with First Class so it is more comfortable and good for your knee or whatever health problem you may have.

Good luck!!