BBM's annual cheerleading set, Dancing Heroine, has been a proven success. After a single set in 2011, the pack-based issue has been split into two releases. And for the past few years, that has included a box set focused on one specific cheerleading team.
At the same time, mascots are huge here, and cards featuring teams' characters are found in BBM's team sets and flagship sets every year. In 2011, BBM issued a box set with cards only of mascots, with an expanded packed-out set in 2013.
The remaining 480 "special" cards are chekis - the Japanese term for an instant Polaroid-style photo. Each Fighters Girl has 13 "solo" chekis, and there are 12 pairings with 14 chekis each. It looks like each cheki is a 1-of-1, with customized messages written on the photo.
It looks like you have a pretty good shot of getting a dual autographed card or a cheki - over half the boxes have one of these two "better" hits. Granted, the chekis are the most valuable. But then again, when it comes to all of these cheerleader sets, the only thing making any one particular autograph or other card more valuable is how pretty the girl is. That is, unless one goes on to be a successful singer or actor or other celebrity.