In order to find the tenth boss of Vongola, the Kokuyo Gang members captured and made Futa rank the Namimori Middle Students' fighting strength. With the list, Chikusa Kakimoto and Ken Joshima, began to attack everyone who are ranked 24th and above. After defeating the fourth one, Tetsuya Kusakabe, Chikusa meets and challenges the third one, Hayato Gokudera.
Gokudera accepts the challenge, saying that he never refuses a fight when invited. Two bystanders go to watch the two but Chikusa Kakimoto attacks them with poisonous darts, killing them. Chikusa then attacks Gokudera, grazing his cheek. Gokudera runs around a corner and, with Chikusa following him, attacks with multiple dynamites. However, Ckikusa is able to defuse them with a yo-yo and attack Gokudera with more needles which explodes. Gokudera is able to dodge and thinks that Chikusa is not an ordinary Middle School student while Chikusa thinks that Gokudera is a professional hitman.
Gokudera asks Chikusa which family he is from but Chikusa did not answer, saying to himself that he got the right one. Chikusa attacks with needles again, asking Gokudera who are the members of his family and the boss. Gokudera dodges the attack and realizes that they're after Tsuna, causing him to attack with his Double Bombs. However, Chikusa easily defuses them with his yo-yos again and attacks Gokudera from two sides. Knowing that his speed is not enough, Gokudera pulls out his Mini Bombs and uses it to propel himself forward to punch Chikusa.
Chikusa dodges the attack but Gokudera immediately pulls out his dynamites and uses Double Bombs again. Chikusa manages to destroy the bazooka but it turns out that Gokudera had mixed some Mini Bombs with the dynamites, injuring Chikusa. As Gokudera explains his strategy, more dynamites fall toward Chikusa, seemingly defeating him.
Tsuna then arrived to warn Gokudera, who (believing himself to have won) gave away Tsuna's position as the Tenth boss of Vongola. Chikusa revealed himself to be grievously wounded but conscious, and attacked Tsuna. However, Gokudera stepped in the way, took the attack and fell unconscious. Yamamoto arrived just in time to push Tsuna away from another attack and upon noticing Gokudera, cut Chikusa's yoyo with his Katana. Upon noticing the police's arrival Chikusa then retreated.