Wikia

The Bermuda Triangle, written as Bermuda △ in Japanese version (バミューダトライアングル Bamyūda Toraianguru), are a clan from the nation of Magallanica that seems to consist of mermaid idols. They center around returning their own rear-guard back to hand to call them again and reuse their effects. Bermuda Triangle was also the first clan given a booster set that was completely centered around them. Emi Sendou and Mai Tobita uses this clan in the anime.

Sets containing Bermuda Triangle cards

Booster Sets:

Booster Set 2: Onslaught of Dragon Souls (4 cards)

Extra Boosters:

Extra Booster: Banquet of Divas (35 cards)
Extra Booster: Dazzling Divas (35 cards)

Races

Shared Races

Mermaid

Sub-Clans

PR♥ISM

List of Bermuda Triangle cards

Grade 0

Angelic Star, Coral (Mermaid)
Bermuda Triangle Cadet, Caravel (Mermaid)
Bermuda Triangle Cadet, Riviere (Mermaid)
Bermuda Triangle Cadet, Shizuku (Mermaid)
Bermuda Triangle Cadet, Weddell (Mermaid)
Comical Rainie (Critical) (Mermaid)
Cooking Caspi (Draw) (Mermaid)
Costume Change, Alk (Mermaid)
Dolphin Friend, Plage (Mermaid)
Drive Quartet, Bubblin (Draw) (Mermaid)
Drive Quartet, Flows (Heal) (Mermaid)
Drive Quartet, Ressac (Stand) (Mermaid)
Drive Quartet, Shuplu (Critical) (Mermaid)
Gunslinger Star, Florida (Critical) (Mermaid)
Heartful Yale, Fundy (Draw) (Mermaid)
Mystery Smile, Aral (Stand) (Mermaid)
PR♥ISM-Miracle, Adria (Draw) (Mermaid)
PR♥ISM-Miracle, Canaria (Critical) (Mermaid)
PR♥ISM-Miracle, Irish (Stand) (Mermaid)
PR♥ISM-Miracle, Timor (Heal) (Mermaid)
PR♥ISM-Smile, Koro (Mermaid)
Sleeping Beauty, Mousse (Stand) (Mermaid)

Grade 1

Grade 2

Grade 3

Trivia

Drive Quartets are the idols that always connected each other.
English versions for Bermuda units from Booster Set 2: Onslaught of Dragon Souls have the full name of the clan (Bermuda Triangle) written, when the japanese versions have a triangle in place of the word "Triangle".
In the Jounetsu-ism ending for the Anime, the deck the viewer uses when shuffling decks with Aichi is a Bermuda Triangle deck. The deck shows Mermaid Idol, Flute, Top Idol, Aqua, Top Idol, Riviere, and finally Top Idol, Pacifica.
Seems as though many Bermuda Triangle units return to the hand, which also can be characterized as "disappearing", it may relate to the real-life Bermuda Triangle where boats/planes would unexplainably disappear, though scientists later suspected that some kind of storm energy caused the boats/planes to be transported to another "dimension".