Chikusa Kakimoto challenges Gokudera to a fight. Gokudera accepts the challenge, saying that he never refuses a fight when invited. Two bystanders go to watch the two but Chikusa 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 explode. 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 Gokudera mixed some Mini Bombs with the dynamites, injuring him. As Gokudera explains his strategy, more dynamites fall toward Chikusa, seemingly defeating him.
Tsuna then arrives to warn Gokudera, who (believing himself to have won) gives away Tsuna's position as the Tenth boss of Vongola. Chikusa reveals himself to be grievously wounded but conscious and attacks Tsuna. However, Gokudera steps in the way, taking the attack and falling unconscious. Tsuna begins to panic as Chikusa gets ready to attack him too...
Note: Bold + Italicized = First Appearance