In our 33 years of dealing exclusively with Japanese baseball cards and memorabilia, we have never seen this card before. It is almost definitely a first prize or second prize premium from an unknown display sheet, but we have absolutely no idea as to the bromide set for which it is a premium. Since 1948 was Kaoru Betto's rookie year, there is a decent chance that this is a large sized rookie card. Betto, a right handed hitting, bespectacled outfielder is best known to Americans as the player whose visage is seen on the iconic shirt worn by Jeff Bridges in the movie, The Big Lebowski. In 1948, as a rookie, Betto batted .328 with 13 homers. In 1949, he batted .322 with an impressive 39 homers and 126 RBIs. Blank backed.
Size: 5 1/2" x 8 7/8"
Condition: Vg/Ex with extra paper glued to the blank back along the top edge, as the card was originally attached to a display sheet by the manufacturer. Any other examples of this card, if they are ever found, will also contain this extra paper.