Little tip: Don’t make the same mistake I have made before. The Terminal online and on tickets is often just written as TERMINAI “I” and it looks like a “1” (one).
It’s really easy to get it wrong and the two terminals are reasonably far apart.
Haneda International Airport also rents out free baby strollers (for use in the airport.). Stroller rental here is free and can be collected from the information counter or the check in counters.
There is one play space in front of gate 106 & another at 145.
If you are looking for a park that is close to Haneda Airport, I recommend this fantastic option here.
At Haneda Terminal 3 arrivals (just near 7-Eleven) AND on the 4th floor before going through security – you can find a lot of gatcha pon machines.
My kids love these and they are also an excellent way to use up left over Japanese coins.
See here for a detailed blog post on Where to eat with kids in Haneda Airport ? (including places that will heat up baby food or provide boiling water for parents who need to make up baby formula.)