Ail and Ann

Manga: Ail and Ann do not appear in the manga.
Anime: Ail and Ann are aliens from a world that was destroyed. The only remaining part of their planet is called the "Doom Tree," which gives them life and energy. Ail and Ann come to the earth in hopes of reviving their tree by collecting energy for it. To collect the energy, they call upon the "Cardians," which are monsters held on cards.
Name origin:Ail and Ann's names are actually a pun. Put the two names together and you get something akin to Alien. Considering the two characters are in fact aliens, gives them a comical meaning.

Ail (Ginga Seijuurou): Middle English for eilen, from Old English eglan; akin to Gothic agljan; to harm
Ann (Ginga Natsumi): means "blessed with grace."