Wii Fit has entered the Japanese software charts in second position, selling over a quarter of a million units in its first week on sale.
The much talked about fitness title was pipped to the top spot by DS game Prof Layton and Pandora's Box, which sold almost 300,000 units, according to sales information compiled by Media Create for the week ending December 2.
Dragon Quest IV continued to sell well in fourth, as did the PlayStation 2 version of the latest Winning Eleven game in seventh.
Assassin's Creed had a respectable debut in eighth place given the relatively low install base of the Xbox 360 in Japan, and sold just over 40,000 copies.
The complete top ten is as follows:
1. Prof Layton and Pandora's Box (DS)
2. Wii Fit (Wii)
3. SD Gundam G Generation Spirits (PS2)
4. Dragon Quest IV (DS)
5. Sengoku Basara 2: Heroes (PS2)
6. Mario Party DS (DS)
7. World Soccer Winning Eleven 2008 (PS2)
8. Assassin's Creed (360)
9. Mario and Sonic at the Olympic Games (Wii)
10. Yu-Gi-Oh! Duel Monsters World Championship 2008 (DS)