As mentioned by Carter in a comment posted earlier this morning, and now confirmed by multiple additional online sources (like Sanspo, Sponichi, Nikkan Sports, and Daily Sports), the Orix Buffaloes are expected to make an announcement later today that they managed to sign Kei Igawa.
The Sponichi report adds that Igawa's agent, Toru Mihara, arrived in Japan on March 23 and has been conducting negotiations with a team (or teams) in Japan.
UPDATE @ 4:05pm - The Buffaloes held a press conference to announce the addition of Igawa. He was also assigned the number 29.
UPDATE 3/29 @ 4:38am - Igawa got a two year deal worth a total 200M yen plus incentives.