Doppelgangers

Doppelgangers are some of the main villains in Season 2. Each Lucky Bestie has a doppelganger. The Lucky Bestie that corresponds to their doppelganger has to cleanse their doppelganger's heart. If successfully doing so, they may receive their Heartful Lucky Gem. Doppelgangers can also use negative energy or thoughts, feelings or words turned into negative energy to take control of their Lucky Bestie counterpart, gaining that Lucky Bestie their Unlucky form.

List of Doppelgangers

 * Silvana/(Unlucky*) Disharmony - Arle's doppelganger. Her heart was cleansed in Episode 2 of Season 2, and she now fights alongside the Lucky Besties, using a Microphone-like item and attacking by singing and sending soundwaves to her opponent, like Arle. After her heart has been cleansed, she is slightly shy and gets nervous easily, but is still serious and calm. She is shown to have feelings towards Arle.
 * Bella/(Unlucky*) Treats - Trixie's doppelganger. Her heart has yet to be cleansed. She is stated to be somewhat of a yandere, and took control of Trixie in Episode 4 of Season 2.
 * Nekura/(Unlucky*) Monotone -Akari's doppelganger. Her heart has yet to be cleansed. She is stated to be a pessimistic girl who only cares about herself and is very picky about who she wants to be her friends. Nekura is a yandere, often wanting certain people to be her friends and is refusing to share them with others (her 'enemies'). It is also noted she spies on people. She took control of Akari in Episode 7 of Season 2.
 * Azami/(Unlucky*) ??? -Akira's doppelganger. Their heart has yet to be cleansed. They took control of Akira in Episode 8 of Season 2.

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*The "Unlucky" before the Doppelganger's transformed forms is an unofficial naming, confirmed to be unofficial in Episode 2 or Season 2 when Lucky Harmony, now taken control of, introduces herself as Unlucky Dissonance.