Thanks a lot for all the answers.

I agree with MJM. I think that after the long flight (and considerable jet lag) I might be too exhausted to take busses, trains or ferries. I used to travel back and forth from Vancouver to Spain and the sleep deprivation was quite bad (going west is way easier for me). My brain is just fried... It might be better to fly that last hop.

AF to HND (Japan Airlines) forces me to spend a night in Paris, and the return leaves Tokyo at mid night. Not very user friendly!

I think AF to NRT has the best plan, doing BRU-CDG by train is not bad for me, it is quite confortable, and the good thing is that it gets to NRT at 8am and the return flight is 21:55. This means I have a full day to do the connections to/from HND and then do HND-TKS-HND with JAL. I can space them quite well that way to avoid troubles.

Thanks again for the answers and the links! ^