Japanese baseball has cheerleaders. Think of that what you will - really, other than eye candy, they don't have much of a purpose. There are actual cheer leaders who orchestrate the chanting you hear at a Japanese baseball game. But the annual cheerleading card sets (Dancing Heroine Mai, Dancing Heroine Hana, and a team box set) sell very well.
The 2015 box set featured the Cheer Dragons, the cheerleading team for the Chunichi Dragons, who play in Nagoya. The release had autographs and cheki (polaroid) autographs, along with "Life Photographs" of the cheerleaders. Of course, there are regular base cards, and a set of eight inserts were also made.
Those inserts came one per box, and feature foil facsimile signatures of two cheerleaders over photos of them in a standing pose. The backs feature two more photos, this time with seated poses.
I probably would have never even thought of building this set if I hadn't come across several of the cards for only 100 yen each at a card show. With only eight cards in the set, it didn't take too much effort to finish it. And since I collect cheerleader cards, it fits right into my collection, but it also serves as my first completed box set-insert set.
All eight cards, front and back, are shown below. The cards look better in person, since the foil doesn't scan well.