Tsuna is grouped with Kyoko for a homework assignment and she is going to visit his house later that day. As he begins to cheer, a man inside a kind of vehicle arrives and slams him to the ground while he introduces himself as Vongola's Weapon Turner named Giannini. Reborn then arrives and is informed that Giannini is there to maintain their weapons due to recent assassination attempts on Mafia Bosses and successors.
The three then heads to Tsuna's house where Tsuna sees his room covered by Reborn's weapons. Gokudera and Lambo then arrive and ask Giannini to modify their weapons too. Although Lambo is not a part of Vongola, Giannini agrees to modify his Ten Year Bazooka in order to examine the legendary weapon. Just then, Kyoko arrives and Tsuna remembers his homework. He then leaves the group, forbidding them from going down to the kitchen.
Tsuna then meets Kyoko at the door and motions her to the kitchen where they begin to start their assignment. Kyoko then sees Tsuna's old essay and begins to read it out loud. She laughs at it, calling Tsuna cute, while Gokudera arrives at the kitchen, crying as he was touched by the essay. Gokudera tells Tsuna that he came down to let him see his newly modified weapons and immediately throws his dynamites. However, instead of exploding, birds appeared out of midair, angering Gokudera who leaves to confront Giannini. Reborn then appears and tries to shoot Tsuna with his newly modified gun but sees that its power decreased. An annoyed Reborn then leaves to deal with Giannini too. Gokudera and Reborn beat up Giannini causing Tsuna to check on them. Suddenly, Lambo uses his newly modified bazooka on himself. At first, nothing seemed to happen, but Tsuna notices that Gokudera has been changed into a baby. However, Gokudera seems to be unaware of his condition and leaves. Tsuna decides to follow him in order to hide him from Kyoko. However, it was too late since Gokudera is already arguing with Kyoko and is trying to use his dynamites on her. As Tsuna stops him by carrying him, Gokudera seems to see something that is invisible to Kyoko and Tsuna's eyes.
Meanwhile, at the pole outside Tsuna's house, two assassins wearing some optical camouflage are beginning to make a plan to assassinate Tsuna...
Note: Bold + Italicized = First Appearance