After emerging victorious from a brutal underground tournament, Baki Hanma continues on his path to defeat his father, Yuujirou, the strongest man in the world. However, he gets no time to rest when the tournament runner, Tokugawa Mitsunari, visits him at school. He reveals to Baki that five incredibly dangerous death row inmates from around the world—all skilled in martial arts—have simultaneously escaped confinement and are heading to Tokyo, each wishing to finally know the taste of defeat. Tokugawa warns that, due to his well-known strength, Baki is bound to encounter them sooner or later, and he will not be their only target. Adapting the first saga of the second manga series, Baki centers on the all-out war between the esteemed martial artists of Japan and those of the dark underground world.

In his father's absence, teenager Ippo Makunouchi works hard to help his mother run her fishing boat rental business. Ippo's timid nature, his lack of sleep, and the sea smell make him an easy target for relentless bullies who leave him bruised and beaten on a daily basis. Mamoru Takamura, an up-and-coming boxer, rescues Ippo from a violent after-school incident and takes him back to the Kamogawa Boxing Gym for recovery. Takamura and his fellow boxers, Masaru Aoki and Tatsuya Kimura, are stunned by Ippo's powerful punches—a result of strong muscles developed through years serving his physically taxing family business. Following brief training under Takamura, Ippo impresses the other boxers in a practice match against prodigy Ichirou Miyata. He gains a rival in Miyata and a coach in Genji Kamogawa, the gym owner and a former boxer himself. As Ippo takes the first steps in his official boxing career, he faces off against a series of challenging opponents, each more powerful than the last. Victory, loss, and a cycle of dedicated training await Ippo on his journey to achieve greatness. With his tough body and unstoppable fighting spirit, the kind young man seeks to take on the world.

Japanese Featherweight Champion Ippo Makunouchi has successfully defended and retained his title. Meanwhile, his rival, Ichirou Miyata, has resurfaced in Japan, aiming for his own Featherweight belt in the Oriental Pacific Boxing Federation. When the rest of the world comes knocking, however, will Japan's best fighters rise to the challenge and achieve glory at the top? Or will the small island nation be crushed under the weight of greater entities? This time, champions will become challengers issuing a call to the rest of the world and ready to show off their fighting spirit!

In professional sumo, there are no weight classes. It's a savage sport where the strongest survive, and anyone willing to test their mettle can step into the ring. There is, however, a minimum size requirement to be a pro sumo wrestler, and young Hinomaru Ushio, incredibly talented and hardworking though he may be, does not meet that requirement. This small boy has big dreams of reaching the highest class of sumo, Hinoshita Kaisan. The only way he could possibly go pro is if he becomes the High School Yokozuna, a title given to the strongest wrestler in high school tournaments. Ushio is under a lot of pressure, as well as a time limit. If he can't show off his skills in the high school tournaments, he may lose his chance to go pro permanently, and the odds are stacked against him. Instead of enrolling in Ishigami High, the best school for sumo in Japan, he enrolls in Odachi High and must build a sumo club from the ground up with the one devout member Shinya Ozeki. Odachi High is the true underdog of the sumo world, but Ushio has to push forward with all his strength if he is going to make it professionally.