So far I've come up with a list of
NOTE - this does not include any players who attended spring training in the US or played in the World Baseball Classic. And to be honest Morimichi Takagi's case is probably borderline.
|1975 NST blank backed parallel|
|1993 Tomy #295|
|2002 BBM Pacific League Champion Lions #L1|
|2012 BBM Celebration Of The Hawks #22|
|2009 BBM 1st Version #253|
|2015 Calbee "Managers" #M-05|
|2015 BBM Eagles #E01|
|2017 Epoch Carp #01|
|2018 BBM 1st Version #001|
|2018 BBM Marines #M01|
|2019 BBM Dragons #D01|
|2020 Epoch NPB #397|
Five of the current managers in NPB have played professionally in North America - Iguchi, Kudoh, Ramirez, Takatsu and Yoda. I believe that is the largest number of such managers at any one time in NPB history.
One last piece of useless trivia on this topic - there is only one NPB team that has never employed a manager who has played professionally in North America - the Yomiuri Giants.