Rivalry Battle

Having cleared the first stage, Kunigami reaches the assembly area and finds Chigiri, only to learn that Isagi, Bachira, and Nagi have already moved on without them. Both bristle at the news, then agree to pair up and hunt for a third member. Meanwhile Ego lays out the third stage: three squads clash in a single game that ends when one side reaches five goals, each defended by a Blue Lock Man in net. The twist is that the victors may seize a player from a defeated team, swelling to a four-man unit while the losers drop back to repeat the prior stage. Repeated through the fifth stage, this builds each winning team up to five players, a format Ego names the rivalry battle.

Ego then posts fresh rankings based on the order players cleared the first stage: Isagi lands fifteenth, Bachira sixteenth, and Nagi seventh. On Rin's side, an anxious Tokimitsu frets that a loss would leave him unchosen, while the style-obsessed Aryu grumbles that beating so-called potatoes like Isagi would look unimpressive and that they should target the top ranks. Rin cuts him off, indifferent to any opponent and eager only to win fast and advance. He admits he grouped with the pair merely because the stage demanded three, regarding everyone in the facility as a stepping stone, and reveals that his football is driven entirely by the desire to crush Sae Itoshi.

The revelation stuns Isagi, who realizes Rin is the younger brother of the celebrated midfielder Sae. Bachira laughs at Rin's raw ego and Nagi notes how strange their opponents are. Though Isagi knows the trio is a fearsome matchup, his own ego insists he take them on, so he apologizes to his teammates and challenges Rin's group. Bachira and Nagi back the call, Rin shrugs that any opponent will do, and all six players head into the third stage together.

Ego explains the rivalry battle format, where winning teams absorb a player from the losers until each reaches five members by the fifth stage. New rankings place Nagi seventh, Isagi fifteenth, and Bachira sixteenth. Rin is revealed as Sae Itoshi's younger brother, obsessed with defeating him, and his trio agrees to face Isagi's team.

Titled Raibaruri Batoru, this twenty-page chapter continues the Second Selection Arc in Volume 6 and is adapted in Episode 12. It introduces Aryu and Tokimitsu and sits between Chapter 43 and Chapter 45.