Katekyo Hitman Reborn!

Kyoko's friend Hana is infatuated with Future Lambo and blackmails Tsuna into letting her meet him by threatening to tell Kyoko that Haru is his girlfriend. When Lambo uses the Ten-Year Bazooka, however, something malfunctions and creates a teen Lambo with young Lambo's mind, and to make matters worse, this Lambo escapes from the house.