We are then taken to Tsuna's house, where an explosion occurs from his room. Nana Sawada is cooking downstairs and comments on how much fun they're having. Tsuna, surrounded by wreckage, questions Reborn on his policy of activating explosives every time Tsuna incorrectly answers a question. They proceed onto the next question, and outside we see the same cowprint-clad child from before, Lambo, standing on a tree outside Tsuna's window, holding a variety of weapons. He tries to shoot Reborn, but the tree branch cracks and he falls down. On the ground, he tries to prevent himself from crying, and after composing himself, rings the doorbell. Nana answers and invites him in after he introduces himself as Reborn's friend.
Upstairs, he throws open the door to Tsuna's room, but Reborn continues to ignore him, continuing to teach Tsuna math while deflecting Lambo's attacks. When Lambo is finally sent flying into a wall, he breaks down crying, introducing himself as Lambo-san, the five-year-old hitman associated with the Bovino Famiglia whose greatest rival was Reborn. Tsuna is dumbfounded at his actions, but Reborn continues to ignore him. Lambo, then seriously angered, brandishes a grenade and tries to throw it at Reborn, but Reborn sends both Lambo and the grenade flying out the window. After the explosion, Reborn explains that he doesn't associate with people ranked lower than him.
Later that afternoon, the purple-haired woman from the airport walks down Tsuna's street, looks at his house, and turns away.
The next morning, Tsuna runs out of his house, late for school. He sees the same woman from before on a bicycle, and she tosses him a can of soda. Being incredibly nonathletic, Tsuna drops the can onto the ground, and it spills. As he goes to reach for it, a purple gas rises from the liquid and kills a bird flying overhead. In shock, Tsuna makes his way to school.
At school, Gokudera and Yamamoto argue about who was more fit to become the right-hand man before Hana Kurokawa and Kyoko arrive. Kyoko gestures at Tsuna's leg, and he notices that Lambo is hanging on. The arrival of Kyoya Hibari scares Tsuna, and he run away, saying that he will return Lambo. Outside, Tsuna tries talking to Lambo, but Lambo gets distracted when a secret door opens and Reborn pops out. After Lambo is defeated once again, he reaches inside his afro and pulls out the Ten Year Bazooka, which he uses on himself. Adult Lambo shows up and explains the purpose of the Ten Year Bazooka: the user is switched with their future self for five minutes. He states that he has gotten much more powerful over the last ten years and attempts to defeat Reborn with his Elettrico Cornata, but fails and runs off crying. Tsuna observes that he hasn't changed at all.
Later, at lunch, Tsuna, Gokudera, and Yamamoto are on the school's roof. Tsuna opens his lunch, only to find worms in it and the same purple gas as before. Gokudera appears to recognize it, and Reborn warns Tsuna not to eat it, and calls Bianchi out. Gokudera recognizes his sister, and passes out. Bianchi approaches Reborn and asks him to go back to Italy with her, to which Reborn refuses. Bianchi then leaves.
Inside the infirmary, Gokudera wakes up and explains about his past: at a piano recital, he had been fed Poison Cooking and played the piano haphazardly. However, the crowd loved it and demanded more, so after that, Gokudera's father always made him eat Poison Cooking before performances and that was the reason why he became sick every time he saw Bianchi.
Later, the girls showed up to present the cooking they had made in class to the guys. Tsuna sees Bianchi swap Kyoko's cooking with her own, and prevents anyone from eating it. Reborn sees this and shoots Tsuna with the Iron Stomach Bullet. Tsuna eats not only Bianchi's cooking, but everyone else's as well. When Lambo arrives and sees that there was no more cake left, he switched places with his future self. Bianchi sees him and stands there shocked. Inside the infirmary, Gokudera remembered that Bianchi's previous boyfriend, Romeo, looked like Adult Lambo. Bianchi then smashes her cake into Lambo's face.
When Tsuna goes home, Reborn introduces Bianchi as Tsuna's new tutor, though they have differing reasons as to why she was there.