Weekly Baseball occasionally includes cards as premiums with their magazines. I'm not sure exactly how often. But in 2012 and 2014 at least, they included preview cards for the two annual BBM cheerleading Dancing Heroine sets.
As I've built up my SCM promo card collection, I have picked up some of these cards, but for the past few years I haven't made any progress. In fact, both years had four cards each, and I've had three of four cards for each year.
Last month, I finally found one of the cards I needed. Along with the three I already had from that year. Each pair of cards were included in a little envelope of sorts attached inside the magazine. One seller had both envelopes for the 2012 set. Let's have a look at this issue, shall we?
The Dancing Heroine Hana (華) promos were included in the June 18 issue.
Card WB1: Akiko Kamishiro, Fighters Girl (Nippon-Ham Fighters).
Card WB2: Chiho Abe of Team Venus (Yomiuri Giants).
Dancing Heroine Mai (舞) promos were included in the July 30 issue.
Card WB1: Asami of the Honeys (Fukuoka Hawks).
Card WB2: Riho Sugiura of the Cheer Dragons (Chunichi Dragons).
The cards use basically the same design of the base cards. The gold background distinguishes them from base cards, as does the Weekly Baseball Promotion notation on the front and unique card numbers.
As I mentioned at the beginning of the post, I only know of 2012 and 2014 promos. I feel like I've had 2013 and/or 2015 cards, but I could be mistaken. SCM Magazine included cheer promos in later years before it, sadly, disappeared.