Although she´s identical to Relena Norstein, so identical that they could be twins…they are not.
She is Kita Norstein, belongs to Reality 07 and Lunamon is her digimon. Kita is Tohma Norstein´s 07 counterpart ´s daughter but she rarely mentions either her father or the rest of the Norstein family.
Kita insists to be called North and doesn´t bother to use honorifics.
Both North and Lunamon already debuted (albeit briefly) in chapter XVII. North is currently one of Lucemon´s hostages while Lunamon dedigivolved into Moonmon and is currently in reality 02.
When North meets the younger version of her daddy, she won´t be impressed in the least….