Osaka to Kyoto travel on Dec 31, 2019

We are arriving in Kansai Airport on Dec 31, 2019 (2PM). Our original plan was to go straight to Kyoto and stay there for 3 nights then back to Osaka. However, I've been told that travelling by train on this date might be a problem because of holiday rush. There are some information though that the rush will be earlier this yearand Dec 31 travel will be ok.

Would bus transfers be better? Or should we stay in Osaka first then visit Kyoto after New Year's holiday (Jan 6-8, 2020)?

The holiday rush is never on the 31st.

And KIX to Kyoto is only short distance commuter. Not long distance shinkansen or ltd exp.

As PPs said, I would NOT be concerned about the train from KIX to Kyoto.

The one point to research though is the opening days of the attractions you want to visit between 31/Dec and 4/Jan. After 4/Jan everything should be back to normal but those first (and last ) days of the year many places are closed. This is true for Kyoto we well as for Osaka.

If you are in Kyoto the first days of the year my personal recommendation is to go to Fushimi Inari shrine. It will be CRAZILY crowded, but at this time of the year not only by tourists but by local worshippers.

Enjoy your trip to Japan!

OP here. Thanks for the responses. More confident in sticking to our itinerary and bookings.