I've learned that last year Darrell Oliver announced his retirement, but now he's back! The other two pitchers: Pedro Feliciano and Jose Parra are part of an MLB-NPB exchange program of mediocre pitchers.
The Mets have not had a lot of success with Japanese pitchers. Ishii, Hideo Nomo, Takashi Kashiwada, Satoru Komiyama, Shingo Takatsu. Masato Yoshii would be the only one who would be considered "not terrible" during his Mets tenure.