Dear Falco,
That makes sense. I see that the flight is quite full for AF, quite empty for JAL.
I shall try to get a good seat when checking in.
One information I suppose usefull (I read you have connections at AF !) : I generally check in at provincial airports. When the flight is a codeshare, AF always tells it is not possible to have intersting seats. When connecting in Paris (thanks to the lounge dragon) it is possible.
One thing more : they do not add the yellow sticker "Elite" on operated flights : I missed a connection in IAH (AMS LAX CO operated, coming from France (TLS)) because my luggage was late (fortunately, that gave me additional miles, because AMS LAX is obviously shorter than AMS IAH LAX, and CO has a "same number changing plane flight". One month later, I waited 1 hour at SCL for the luggage, this was less funny).
To Japan : I shall only have one small rucksack hand luggage (less 10 kg and not 12) and a 22' roller checked luggage (15 kg approx).
I wonder if it will be OK with the lounge at NGO.