Reborn, Tsuna, Lal Mirch, and Mammon are on the roof of a building. Mammon tells them that Box Weapons have recently been showing up in the Mafia. Mammon explains that they (Mammon) had been paid to test them out by Verde. Lambo appears on a fence, exclaiming that he wants more of the "shiny sparklers"; in other words, the Arcobaleno Seals. At the Sasagawa residence, Ryohei congratulates Tsuna on yet another trial passed. Tsuna expresses his worry at the appearance of Box Weapons and Lambo suddenly runs by, asking where the "chrial" is. I-Pin explains why he wanted to clear more trials, and Reborn orders Tsuna to bring Lambo back. Running past Namimori Middle, Tsuna notices a strange figure on the roof, but takes no notice of it and yells for Lambo to come back.
Meanwhile, Yamamoto goes home to his family's sushi place and notices Belphegor and Mammon there, with the same strange figure sitting at one of the stools. Gokudera, at the convenience store, also sees the figure reading a book, while Ryohei, on a jog, notices the figure sitting on a slide at the park.
The next morning, Nana calls to Tsuna that he has a letter. It reads, "catch me if you can," with a picture enclosed. All three of the Guardians who had seen the figure last night comment at the same time that they had seen him and all three leave to their own respective places. I-Pin recognizes her master, and Reborn comments that the Arcobaleno with the red Arcobaleno Pacifier is none other than Fon, I-Pin's master. Tsuna remembers that he had seen Fon at Namimori Middle and departs with Lambo.
Gokudera, Yamamoto, and Ryohei have no luck with finding Fon. At Nami Middle, Tsuna meets Haru, who happens to be walking by. On the roof, Fon reveals his true self and explains that all they have to do is catch him by noon to pass his trial of leadership. Tsuna is worried because the only other people there are Haru and Lambo, with Lambo being the only Guardian. He does not, however, notice that I-Pin is also there.
Tsuna, Haru, and Lambo fail repeatedly to catch Fon, while in the gym I-Pin has a flashback of a lesson in which Fon had instructed her to catch falling leaves. She was unable to because she had gone against the wind. At the end of her flashback, she realizes that the three had been doing just that.
Eventually, the three come up with a plan to lure Fon into the art room, which ultimately fails. As Fon is about to run outside the art room, I-Pin appears in the doorway to stop him, saying that she wanted to make everyone happy. She briefly duels Fon before using Gyoza-Kempo on Lambo, causing him to fly into Fon. Fon flies across the room, straight into Tsuna's arms. Seconds later, the clock strikes noon. Lal announces that Tsuna has passed his trial and informs Tsuna that I-Pin had been there from the start. Fon remarks on Tsuna's leadership qualities and how that was what led to his success. Tsuna then receives Fon's Seal.