This extra chapter details the backstory of Kodoh Kuraki during the days of his training.
In the isolated training island of the Magajin, several kids are pitted against each other in a survival game where the last man standing will become one of the Successors. Kodoh Kuraki (Number 42) was gaining the upperhand before he finds himself surrounded by several bloodthirsty competitors. One of the competitors were able to shoot off Kodoh down the cliffs where he fall straight into the open waters.
As soon as Kodoh opened his eyes, he finds himself in an encampment and fortunately, still with his badge. A gentle-looking competitor that introduced himself as Teruma Kamioka (Number 13) retells that he fished Kodoh out of the water. Teruma offered Kodoh a meal but seeing that they are both in the game, Kodoh walks out and eats grass. Teruma insisted on giving Kodoh a meal and the two talked amongst themselves.
Meanwhile - another competitor, Kyousuke Arasaki, finds himself entering the same bloody competition.
On the third day of the Survival Game, Teruma decided to exhibit some of his abilities to Kodoh by shooting a tree of apples. Teruma accidentally shot a Beehive and the bees all chased after him. Kodoh helps him out of this and the two went on to the next one despite Kodoh still being aloof with Teruma by his side.
Teruma asks for Kodoh's age. Kodoh reveals himself to be 6 years old while Teruma revealed that he is 7 years old and also commented that it makes him an older brother to Kodoh.
The 9-year-old Kyousuke is eavesdropping on the two from a tree while admiring Kodoh's skills and at the same time being jealous of Teruma and Kodoh's companionship. He soon finds himself an open target and he collapsed from a gunfire.
On the fifth day, Kodoh challenges Teruma to a battle.
On the Seventh Day, Kodoh and Teruma's hideout was discovered by the other competitors. Kodoh finds himself surrounded so Teruma steps in to distract the others. However, Kodoh was shot and Teruma tried to fight back but his willpower is too weak, let alone his physical prowess.
Teruma decided to sacrifice himself by shielding the wounded Kodoh and taking all the hits from the other players. Kodoh stands up and finally gives his name to Teruma. Enraged by what happened to his friend, Kodoh stands up and declares his name to all competitors. Teruma gives Kodoh his B-Daman and from there, Kodoh became unstoppable. In a state of frenzy, Kodoh took down opponent after opponent. Teruma laid down with the last of his strength, watching as the two of them are the last ones that remained standing.
Meanwhile, Kyousuke was gunned down and insulted by an anonymous competitor. This awakened the supressed monster from within him. Kyousuke gets up frenzied and the competitor could only scream in horror.
Back to Kodoh and Teruma. A helicopter arrives and the boss himself alights from it. He is introduced as Doctor Shou and he steps in to congratulate both Kodoh and Teruma for having survived the ordeals of the island.
Shou is surprised that only the two made it out alive and that certain person surprisingly did not. The three of them were about to leave by helicopter when a third survivor arrived bloodied and dragging his last unfortunate victim. It's none other than Kyousuke Arasaki (Number 99) whose forehead emblem is exposed and has an evident sadistic expression in his face.
Kyousuke comments that he has not had enough of his victims yet and he wanted to play more. Shou realized that he could not keep Kyousuke's power at bay for at least seven days so he decided to take all three survivors back to the Headquarters.
- Kodoh Kuraki vs Anonymous Kids