^Sometimes they don't use the newest songs. They sometimes use the first song they've had on the year. An example, Pucchi Best 7. Berryz had 3 singles in 2006, Jiriri Kiteru, Waracchaou yo BOYFRIEND and Munasawagi Scarlet. They used Jiriri Kiteru~ We don't really know what song of Momusu, Berryz, Biyuuden or C-ute are gonna use, since they had more than a single this year
Same for Biyuuden, they used Issai Gassai insead of AisuCream to my Purin since it was the first single of the year~.