An A350-900 that most likely will never make it to KUL, as they are meant for domestic flights. Only once the A350-1000 arrives will there be international flights on JAL A350. But maybe they are trying to highlight the domestic connectivity in a round about way? :-D

Most probably since this agreement will cover both end domestic routes too (Rarely they use big plane unless it is election time [a380 for KUL/PEN lol] or flying between East Malaysia and Singapore in a330):D
Or
They just matching the same plane in the banner since it looks better with both airlines having same airplane model:D
Or
Probably they going to use A350 for kul route somewhere in the future but highly unlikely as they used 767/787 size plane past few years. The last time they used 777 during the old days before they went down under. Probably 787 size plane was just right for what it does. Also this route is one of launch route (other is one China route) for Sky Suite III too so i supposed this route is valuable in away for JL. Ground staff told me the load prior to Covid-19 is quite high on daily basis.:confused:

The bolded one is probably the most likely. As KUL never saw a JL 77W on a scheduled basis and the A350-1000 are supposed to be the 77W replacements, I doubt that we will see JL A350 scheduled on the route. But who knows, there may benew and strange fleet re-jigs once we are out of our current travel restrictions.

Another note is that MH will always rotate its a380 for tokyo route (before Covid-19). Maybe both side were eyeing on different market segment (eg Business Traveler/Connecting pax to NA versus Leisure Traveler).

I have no chance to sit in JL international 777 yet. The closest one i can board is via SIN but then it will take much longer to arrive in Tokyo (versus 6am arrival if take JL directly from KUL) and chances of KUL-SIN leg via MH part getting cancelled/delayed is quite high too (well, Malaysian timing lol:p).