Back in the 1980's and 1990's, some Japanese teams had working agreements with some US major league teams and the occasional independent minor league teams. (In this case, I mean a team that plays in an affiliated minor league like the California or Carolina league but has no major league affiliation. These teams have become extinct in the past 15 years or so.) These working agreements would usually include the Japanese teams sending players to play in the minors in the US. (I assume that there was a well understood agreement in place to prevent the Murakami incident from being repeated.)
As it happened, many of the minor league teams that the Japanese players appeared on had baseball card sets. I've been looking through my own collection of minor league cards and checklists to see what I can find. Japanesebaseball.com has a partial list of players. If I get a chance, I'd like to update the list and make a couple of corrections (the Masahiro Yamamoto that's listed as being with San Jose in 1988 is not the Masahiro Yamamoto who plays for the Dragons).
San Jose had a working agreement with the Seibu Lions during the 1980's. It looks to me like they originally signed the agreement when San Jose was independent and it continued for a few years after they got a working agreement with the San Francisco Giants. Ken Suzuki was with the 1988 team. Here's his card from the ProCards team set:
Also in 1988, the Miami Marlins had an agreement with the Yomiuri Giants. Masao Kida made his first of three stints in the US with the team that year. Here's his card from the Star team set:
It turns out that there were two Masahiro Yamamoto's playing in the US in 1988. The one with San Jose briefly appeared with the Lions in the early 1990's. The one with Vero Beach (the Dodgers must have had something going with the Dragons) is the one who just got his 200th win. Here's his card from the Star team set:
Yamamoto actually pitched well enough that year to make the Florida State League All Star team. Jason Presley has that card in this gallery, along with some other Japanese players from his minor league sets.
The Hawks had an agreement with the Salinas Spurs of the California League for a couple of years in the early 1990's. In 1990 at least, this included not only providing players but also the manager. Here's the Cal League card of Hide Koga, the first (and possibly only) Japanese manager in US professional baseball:
I think the "study abroad" program petered out in the early 1990's. While US teams still have agreements with NPB teams, it doesn't appear that players come to the US from Japan to play in the minors anymore. However, there is one place where US and Japanese prospects still play together - the Hawaiian Winter League.
The Hawaiian Winter League (HWB) lasted for 5 seasons from 1993 to 1997. It was revived in 2006. In its first incarnation, the league featured NPB players like Ichiro, Kazuo Matsui and Nobuhiko Matsunaka. The only baseball cards for the league were put out for the 1996 season. (In case someone wants to take issue with that statement due to a couple cards that are supposedly from the 1993 season, I'll qualify that statement as "The only team sets that were for sale that were actually available in the year they were produced were for the 1996 season".)
There were four teams that year and each team set had a Japanese player who would go on to greater things. The Maui Stingrays had Kenji Johjima, but I no longer have that set, so I can't show you that card. The Hilo Stars had Tsuyoshi Shinjyo and I still have that card:
Hideki Okajima was a Honolulu Shark:
Atsunori Inaba was a West Oahu Canefire:
There are cards for the teams in the HWB from the last few years. Since I stopped collecting minor league cards, I don't know who's in them. It may take a few years for any Japanese stars to appear out of them (although Joba Chamberlain is in one of the sets).