Finally took a good look at the numbers. Wasn't there a rental program for Dragon Quest X in Japan? How do subscription fees work for people who are renting it? What about those who are just buying it now for Wii U?
What you actually rent is the install discs, at Tsutaya. It's free and you also get a trial registration code which allows to play for free for one week. After that you can buy a full registration code for around 3500 yen, so basically the game is discounted at Tsutaya.
I'm not sure if they are following up this promotion with a Wii U trial but the Wii one runs on Wii U as well, obviously. You still need a USB stick.
About DQX... I just remembered that Square Enix was offering a 50% discount to download the Wii U version if owned on Wii. Surely that must have had a not insignificant impact on the reported sales.
Maybe someone with a Japanese Wii U could check the eShop charts and see how it's doing?
It's #1 but that doesn't say much. Hokuto no Ken was #1 too when it released. Yesterday it had just above 200 ratings, 4 1/2 stars. Game & Wario is #2, had just above 100 ratings, 4 1/2 stars.
These games are actually well received, people liked the beta on Miiverse too. One said he bought the U for MH but ended up playing the DQX beta because it is so much fun.
I still think the Wii U price is hindering the console's mainstream success. MH could sell more, DQX could sell more, especially to fans of MH. DQIX tried to get extra sales from handheld multiplayer fans and it worked, online multiplayer could do the same on Wii U. If it could tap into the audience that bought the games on Wii.