The story begins when Hiromichi Kojima, the star batter of the fictional Lycaons in Japan's Pacific League, heads to the southern Japanese island of Okinawa to train and bring himself out of a slump. There, he meet Tōa Tokuchi, a 134-kmph (83 miles per hour) pitcher and the undisputed king of a gambling form of baseball called "One Out." At Kojima's urging, Tokuchi signs up with the Lycaons under an unusual contract: he gets 5,000,000 yen (about US$46,000) for every out he pitches, but loses 50,000,000 yen (US$460,000) for every point he gives up.

(Source: AnimeNewsNetwork)

Notes:
- The main story was completed in 168 chapters with 19 volumes on 2006-10-19. An additional side story Giwaku no All Star Sen Hen (疑惑のオールスター戦編) was serialized from 2008-2009 and published as volume 20 of the series.
- Chapter count includes an additional chapter included in the 7th volume.