Luna, known as Ruka in the Japanese version, sometimes romanized as Luca, Luka, or Ruca, (see below), is Leo's fraternal twin sister and a Signer who possessed the front claw Mark of the Dragon. She and Leo aid Yusei Fudo, whom they admire and support, in his Duels. Luna is the younger, frail, calmer, more collected of the twins. Luna tends to get tired right after a Duel. She has the ability to communicate with Duel Monsters after having spent ample time with Duel Spirits in a different dimension during a coma. She and her brother also have vignette series before each episode in the Dark Signers arc known as card of the week.