You can meet Santa Claus between journeys on December 24th and 25th at Haneda Airport. Santa and two helpers will be walking around the lobby giving out candy. On the 24th there are two opportunites in Terminal 2, the first is from 1oam then again from 11.30am. It has not been specified how long he will be available each time. He will also visit in Terminal 1 twice at 2pm and 5pm.
There is nothing on their website yet, but they will post in the next couple of days. It is anticipated that they will also conduct a free Christmas concert as they have done in the past. The website is: https://www.haneda-airport.jp/