I tried :
Lyon, France as Home (2017/05/02 as start date)
Tokyo Narita, Japan (7 days)
Osaka Kansai International, Japan (14 days)
Noumea Tontouta, New Caledonia (14 days)
This told me that "Something went wrong!
No valid route could be found for these destinations, please try another destination"
I added Paris, France with "0 days" as it's a typical stop when flying international from Lyon.
This gave me a result, but the first stop is Noumea and it says "$false - BOOK". The other destinations have a real price.
My route is weird though, does not seem very optimized (I fly around the world once, from France to New Caledonia and back, before going to Japan, which is on the way), but I guess that's another problem!
I had this as well. The home airport was London Gatwick, and the other entries were Bangkok, Khon Kaen, and Singapore.
It seemed to me that it couldn't find a route from London to Khon Kaen (Khon Kaen isn't an international airport), but interpreted that as a zero cost flight. The route it gave me was Gatwick -> Khon Kaen -> Bangkok -> Singapore and the cost for the whole thing was a fraction of what it should have been.
The way to make that route work, by the way, is to go Gatwick -> Bangkok -> Khon Kaen -> Bangkok -> Singapore (or throw Chiang Mai or Hat Yai into the mix). You can only reach Khon Kaen by air through internal flights in Thailand.
While not directly related to your problem with the website, consider taking the train (shinkansen) between Tokyo and Osaka. It is fast, convenient, and leaves and arrives from city center and can easily count as a "thing I did on vacation".
Actually my real intent was to fly to New Caledonia, and on the way there stop by Tokyo, and on the way back Osaka (I have family to visit in these three places).
But yes you are right about the train experience in Japan! I also tried a night bus from Tokyo to Osaka once when I was a student... leave it up to the Japanese to make that a great experience as well! Recommended if you're on a tight budget.
I tried : Lyon, France as Home (2017/05/02 as start date) Tokyo Narita, Japan (7 days) Osaka Kansai International, Japan (14 days) Noumea Tontouta, New Caledonia (14 days)
This told me that "Something went wrong! No valid route could be found for these destinations, please try another destination"
I added Paris, France with "0 days" as it's a typical stop when flying international from Lyon.
This gave me a result, but the first stop is Noumea and it says "$false - BOOK". The other destinations have a real price.
My route is weird though, does not seem very optimized (I fly around the world once, from France to New Caledonia and back, before going to Japan, which is on the way), but I guess that's another problem!