It may contain SPOILERS.
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The Arcobaleno is a group made up of the world's strongest seven. The "I Prescelti Sette" ("the chosen seven") of an era are infants that possess Arcobaleno Pacifiers representing the Dying Will Flames of the Sky. Their Pacifiers glow when a member is nearby.
The Arcobaleno members were formerly adults that were "cursed" into infants in an event known as "The Fated Day." The gathering of the current generation of the strongest individuals was arranged through contracted jobs. The following set was to be gathered by the Representative Battle. The purpose of Arcobaleno is to harness and protect the power of the Tri-ni-set.
When the chosen seven are burdened with the pacifiers, it causes the reduction in size of the bearers. Physically, they bear the resemblance to a toddler.
Thankfully, their abilities and intelligence remain intact. But because of their infantile body, aspects of speech, and stamina can be affected, such as Reborn saying "Ciaossu" rather than "Chaos". In addition to their retained abilities, they can emit Dying Will Flames throughout their entire body. The Arcobaleno are also mentioned to be "walking out of time", meaning that they cannot age or die of old age.
However, the holder of the Sky Arcobaleno Pacifier is an exception. Instead of being cursed with the body of an infant, the holder is cursed with a short lifespan. In Luce's case, she had both curses. The Sky Arcobaleno also has the power to resurrect deceased Arcobaleno by sacrificing their own life.
Over time, an Arcobaleno may weaken and may be unable to hold the power of the Tri-ni-set. Checker Face, the overseer of the Tri-ni-set, removes the Pacifier, leaving an empty stone Pacifier to the former Arcobaleno. The strain of the removal causes the former Arcobaleno to die or become disabled. Few of those who survived become the Vindice, whose primary goal other than upholding the mafia law, is to avenge themselves on Checker Face.
The Arcobaleno, if not the Pacifiers themselves, also form a connection to Checker Face. Who is able to communicate with them via dreams as he did in the "Representative Battle of the Rainbow."
- Interestingly, while Arcobaleno is the Italian word for "rainbow" and arco is an Italian word for "bow or arc", baleno actually translates to lightning.
- There are 10 known Pacifiers, but only 7 spaces on the 7³ (Tri-Ni-Set).
- The color of a Pacifier is the same color as the owner's Flame.
- Interestingly, the Arcobaleno have personalities that are opposite that of their respective flames' roles, whereas the Vongola have personalities that match their respective flames' roles.
- All of the previous and current Sky Arcobaleno have an orange clover mark below the left eye around the cheek, which was later determined as the embed logo of Giglio Nero Famiglia.
- All of the Arcobaleno, except for Lal Mirch, Aria, and Yuni have an animal partner.
- In the opening Listen to the Stereo, Lal Mirch has a blue spotlight because she was supposed to be the Rain Arcobaleno.