Nicknamed "The Red Home Run King" due to his abilities with his red bat, Baseball Mask was recruited by Magman and the Black Cross Führer to save their scientist Doctor Shinigami after the Gorengers apprehend him to prevent him from developing his deadly "Ball Bombs" (ball-shaped bombs with mini bombs to kills anyone hit beyond the initial explosion). Arriving at an EAGLE storage facility, Baseball Mask hits a ball to the scientist containing a pill that kills him, forcing them to send him away for autopsy and allowing for the Masked Monster and his baseball-playing Zolders to regain him. When the Gorenger try to use Gorenger Hurricane against him in the form of a straight pitch, he knocks it back five times hitting all the Gorenger before escaping with the scientist who is ultimately revived keeping with his name.
After bringing back Doctor Shinigami, Baseball Mask protects him for the development of his Ball Bombs, but slowly grows angry at him after he kills his initial Zolder team to test the bomb out, even at the guarantee of having a new Zolder team set up for him. As Shinigami tries to set up a remote version of his Ball Bombs, Kaijo infiltrates and destroys the device forcing out both the doctor and the Masked Monster. After Baseball Mask's bat is slashed by Momorenger's Momo Cards, he becomes even more angered by Doctor Shinigami shooting his prized weapon, allowing his Zolder team to kill him with no complaint.
When facing the Gorenger again with their Gorenger Hurricane, the team decides to use a different strategy: instead of directly throwing a baseball at him, they set him up with a special maneuver, with Momorenger making a ball, throwing it first to Midorenger, who then throws it to Kirenger (who plays catcher for the maneuver) to make a strike; then Daita throwing to Aorenger who throws another strike to Kirenger; then back to Akarenger who throws the final ball but uses an auto controller to confuse Baseball Mask to the point of dizziness with a whirling ball; as he finally collapses, the ball lands on him finally finishing him off.
Kaizoku Sentai Gokaiger The Movie: The Flying Ghost Ship
The Baseball Mask appeared in a pocket dimension of the Ghost Ship many years later. He challenges the Gokaigers to a baseball match, saying he'll let them leave if they beat him in a game. The Gokaigers Gokai Change into the Gorengers and manage to win, with the third strike being a cheat, distracting Baseball Mask with a simulacrum of the G3 Princess.
Kamen Rider × Super Sentai: Super Hero Taisen
When the Den-Liner took Joe Gibken and Don Dogoier with Daiki Kaito and Hina Izumi to Winter 1976, they met Baseball Mask, who was quickly destroyed by Akarenger (later revealed to be Captain Marvelous in disguise).