While Hanshin may be favored to repeat, the rest of the league will be waiting to pounce should the Kansai club falter.
The 2020 National League Cy Young Award winner struck out four and allowed just two hits.
Bauer's quest to return to the major leagues will take him through the Los Angeles Dodgers' facility in Glendale, Arizona.
30-year-old Imanaga has been posted by the Central League's DeNA BayStars.
The 30-year-old led the Central League with 174 strikeouts over 148 innings this year, while having a 7-4 record and a 2.80 ERA in 22 games.
Yamamoto was named to the Best Nine team for the third straight season.
Once MLB notifies its 30 teams that a player has been posted, they will have 45 days to negotiate with him.
The BayStars have given the 30-year-old pitcher permission to use the posting system this offseason.
Imanaga impressed in his two innings as the starting and winning pitcher for Japan in the World Baseball Classic final against the United States in March.