I took the safe path and paid extra for the ability to take 20 kg of luggage per person when I booked the tickets for our Okinawa trip. It was only 10 dollars. But with a family of six, you find that in Japan, there may be better options.
I am Wisterian Watertree, recently moved from Tokyo to Sendai, previously of Bangkong and Honolulu. I write about travel, especially with our three beautiful kids (two girls and one boy, soon turning seven - yes. they are triplets). Travel is education and fun rolled into one, and if you are like me, that is something you want to give to your kids. If you want more tips and want to find out when I will publish something, get it from my email list. If you want to be personal, drop me a note on firstname.lastname@example.org, or if you want general tips, follow me on Twitter @wisterianw.