Bullets are weapons that have played a major role throughout the series. All of the bullets used in the series have different effects.
The Dying Will Bullet is a special weapon created by the Vongola Famiglia. Once it makes contact with a person, they die. If they feel regret when they were shot, they are reborn, not as a baby, but with a flame on their forehead. When reborn, the person loses their clothes (besides their underwear) and are capable of amazing feats. This state is called Dying Will Mode. In the Varia Arc, Tsuna is trained to control the energy of the Dying Will Bullet by maintaining Dying Will Mode for longer than the five minute limit. As a result of this training, Tsuna is able to go into Hyper Dying Will Mode with the shot of a Dying Will Bullet.
The Dying Will Bullet turns all of the person's "safety switches" off, and, in exchange for risking their life, they are able to harness great strength. Through regret, the person shot gains overwhelming strength and power. It can also store and release Dying Will Flames; this technique was used by the Vongola Settimo with the Dying Will Gun because his Flames were the weakest out of all the Vongola Bosses and also by Varia leader, Xanxus, to increase his fighting power.
There are distinctly different bullets in the Dying Will set such as the Iron Stomach Bullet and the Fist Bullet. Each has a specific area that they need to be shot such as head, hand, stomach or feet. For example, when the Iron Stomach Bullet was used, Tsuna wanted to eat Kyoko's cake, but Bianchi swapped it for her poison cooking; so, Reborn shot Tsuna in the belly and turned his stomach into an "Iron Stomach," which allowed him to eat Bianchi's Poison Cooking without harm to himself.
Longchamp Naito often uses this bullet that, because Naito only appears in the manga, is manga-exclusive. Reborn stated that the person who was shot by this bullet will be reborn as they mourn over themselves. So far, the only people who were shot by this bullet were Longchamp, Ryohei, Shamal, and Tsuna.
The Rebuke Bullet was used for the first time during Tsuna's fight against Mukuro Rokudo. This bullet came from Leon's cocoon stage after he lost his tail at the same time that the X-Gloves emerged. The effect of this bullet is for the target to experience real-time rebukes from people that they know. This allows the internal limiters to be lifted and causes the target to enter Hyper Dying Will Mode. The result of the Hyper Dying Will Mode is to increase the battle sense of the user and, in Tsuna's case, greatly increases the Vongola blood trait "Hyper Intuition." This allows him to sense illusions and to read people (both physically and mentally).
The Possession Bullet is a special bullet created by Estraneo Famiglia. It is a bullet that allows the user to take full control over his opponent, and even be able to use their abilities. However, for the bullet to work, the user needs to have a strong spirit and be suited to the bullet. However, due to the cruel way that the bullet was used, the bullet was banned, and all the bullets, as well as the information on how to make it, were destroyed.
However, Mukuro Rokudo, a former Estraneo Famiglia member, still has possession of these bullets. He's compatible with these bullets, and can even use his Six Paths of Reincarnation technique in the bodies of those he possesses, thus allowing him to use multiple paths at once. However, Mukuro can only possess those that he has injured with his trident.
- Reborn mentions that other Mafia Famiglias are now making "altered" versions of the Dying Will Bullets, allowing the user to go into Hyper Dying Will Mode.
- The Rebuke Bullet is translated as the "Criticism Shot" or the "Scolding Bullet" as well.