This volume picks up where the last left off with Maruko informing the aces of Deimon and Seibu about the great risk to the health of their teams; if they play Hakushu, they will face Gao, the bone-breaking player who finds it fun to physically destroy his opponents. (But only if it's within the rules; he is able to calculate, despite the appearance that he is a bloodthirsty monster.)
Now, why did both the Devilbats and the Gunmen get the warning? Oh, because Hakushu assumes Seibu will fall to the Dinosaurs and the Devilbats--specifically Hiruma--will be next in the line of fire. Not forefiting will put them at risk of an injury that may prevent them from ever playing again.
Of course, being who they are, Sena and Riku do not decide to forefit. The game goes on.
We see Gao in action--a powerful heavyweight who plays with a laser-focused fury. We soon learn his team was once nothing, and meet some of his teammates. Deimon's team nervously watches as the members various Devilbats have rivalries with are trounced by the Dinosaurs' power. The Kid remains calm, but even he goes down. Riku's trickery can't stand up to someone like Gao. Tetsuma even goes off the rails for once, but he cannot protect Kid. Deimon will not be able to fulfill their matchup against the Wild Gunmen at the Christmas Bowl. They'll face the Dinosaurs instead, and they must figure out a way to avoid Hiruma meeting the same fate as Kid--he leaves this game with broken bones, and Gao sets his sights on a rivalry with Kurita.
The Devilbats have strategizing to do, and somehow this happens during a game of baseball. The stadium holds some history for Deimon's team, so we get an origin-story flashback . . . featuring child Hiruma, just as devilish before the piercings and hair dye. As a child, he'd sneak onto the American military base and learn gambling games, helping the soldiers part with their money, for no reason really except he likes winning. He discovers football betting as a middle schooler and meets Kurita, who is desperate to start a football club at his school but lacks the required three founding members. After his determination leads to the school officials ordering him to stop practicing on school grounds and get rid of his equipment, he ends up forging an unlikely partnership with Hiruma and Musashi, who repaired a hole in the fence but kicked another one. It's so heartwarming to see Hiruma's idea of fun being enhanced by Kurita's love of the game, and how Kurita has evolved to be the pillar of strength and protection he is now.
With many other previous opponents showing up to help train with the Devilbats, Kurita practices against the Pyramids player Banba and realizes he's got to up his game.
I lovelovelovelove devilish little child Hiruma and any story about Kurita's resolve! This one is a lot of fun despite focusing primarily on a game that the Bats didn't even play in!