It's summer time and Tsuna and his friends goes to the beach to relax. In their bathing suits, Kyoko and Haru are attracting the men's attention. Tsuna watches them, feeling proud about the girls and thankful to Ryohei for inviting them. Kyoko explains to the group that Ryohei is there to assist the older lifeguards, causing Tsuna to think about the time when he was saved by a lifeguard after getting washed out to sea as a boy.
Ryohei then greets them and introduces his colleagues, including Reborn in his his Master Pao Pao costume and the three corrupted lifeguards. The lifeguards then pulls Kyoko and Haru with them, telling the guys to watch the beach. Gokudera and Yamamoto stop them, asking them why do they have to work for them. Ryohei also protests but stops immediately when the lifeguards told him that they wanted to teach Tsuna and the others the glory of being a lifeguard. When the girls also protest, the lifeguards challenge the group to a swimming competition, with the losing side being the winner's slaves. The group tries to protest, but Reborn immediately silents them and accepts the challenge for them. The lifeguards tells them about the rules and Yamamoto decides to go first, followed by Gokudera and Tsuna. Tsuna is afraid of drowning in the ocean but accepts when Kyoko and Haru tell him that they will cheer for him.
Round one begins and Yamamoto's opponent initially gets the lead, saying that they've undergone different training compared to Tsuna's team. Yamamoto merely smiles and overtakes him as the others cheer him on. However, the other lifeguards seem to be confident that they will win. Yamamoto manages to be the first to approach the island and begins to loop around. However, a group of the lifeguard's lackeys are there waiting for him. Tsuna and his friends see that Yamamoto vanished as his opponent loops around the island. The other lifeguards tell the group that they Yamamoto's leg seemed to have seized up and he decided to rest on the island. Yamamoto's opponent then returns to the beach, winning the match.
Round two then begins. As Gokudera and his opponent swims neck to neck. His opponent asks Gokudera where Yamamoto was but Gokudera tells him that he knows that Yamamoto would not let a leg cramp stop him from returning and thinks that he was probably ambushed by the lifeguards' friends. As they round the island, Gokudera is ready and looks at the it, ready to face the lifeguards' friends. However, no one is on the island and Gokudera's opponent tells him that there are a lot of their lackeys underwater who pulls down Gokudera with them. Gokudera's opponent then begins to go back to the beach while his friend tells Tsuna and his group that Gokudera probably had leg cramps too. Tsuna sees that there is something suspicious going on and starts to panic. The lifeguard then tells him that even though Tsuna's team already lost two out of the three rounds, he will allow them to win if Tsuna wins against him. Ryohei tries to go check on Yamamoto and Gokudera but is stopped by the lifeguards who tells him that the two are only communing with nature and to not disturb them.
Round three then begins. Tsuna is worried about drowning but his determination to not let Kyoko fall to the lifeguard's hands allows him to continue swimming. Just then, a woman in the beach points to her child and asks anyone to help her. Tsuna sees the kid being washed out to the ocean. Tsuna tries to get the lifeguard to stop and save her but he refuses, saying that he only became a lifeguard to pick up chicks not to swim to dangerous zones. Tsuna sees the girl scared and decides to go help her instead, surprising the people in the beach. The lifeguard tells him that the sea isn't kind and forgiving and Reborn swims behind Tsuna, agreeing with the lifeguard and tells Tsuna that he will not shoot the Dying Will Bullet. Tsuna ignores him, determined to save the child, knowing what it was like to be like her. Tsuna reaches the girl but begins to sink himself. Reborn thinks that it's very Vongola-like and shoots him with the bullet, causing him to recover and bring the child back. The other lifeguards are surprised to see this, but think that their lackeys will stop Tsuna from going back. However, Yamamoto and Gokudera arrive, bringing with them the beaten up lackeys.
Tsuna's opponent tries to stop Tsuna from taking all the glory and tries to snatch the girl away from him only to be punched in the face by Tsuna. Tsuna manages to save the girl but, without the dying will flame, no one believes him.
Note: Bold + Italicized = First Appearance