SLPM-84003 ケロッグ ワクワクドキドキ人気 ゲームキャラ大集合! ワクワク賞
SLPM-84003 Kellogg Waku Waku Doki Doki Ninki GAME CHARA Daishuugou! Waku Waku Shou
From what I've figured out, a trading card was included in every Kellogg's corn flakes box, with a random hero from Konami, Namco or Capcom games. Sometimes, if you were lucky enough, you could get a special card that you had to send back to Kellogg's Japan in order to win a special demo.
There exist 2 different demo compilations (Dokidoki and Wakuwaku versions).