Kojima is the cleanup batter in the professional baseball team, Saikyou Saitama Lycaons. He is defeated by Toua during his time at the training camp as he challenged Toua to avenge his relief pitcher, Nakane. After his defeat, he goes into the forest to train himself mentally against Toua but as he is training he injures his wrist. Even with the injury he challenges Toua to a rematch with the bet that if he wins, he takes Toua&#039;s hand. He wins the match as he gets hit by the pitch making it a deadball, Toua admits defeat and Kojima makes Toua join the Lycaons. (source: wikipedia &amp; manga)  

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 meets Toua 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: Anime News Network)

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 T&#333;a 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.