Not much is known about Karina, she is Venger's sister and appears in the episode Citadel Of Shadow. She appears as an innocent girl who calls for help. Hearing her, Sheila and Uni go to her aid. As Sheila saves Karina, she says that she has to take back a red ring that her brother stole from her and locked in the Citadel Of Shadow.
While Sheila is trying to take the red ring, Karina suddenly reveals to Uni an evil personality of hers, as she prevents Uni from screaming and calls Sheila back. When the others find Sheila and Karina at the Citadel, Venger appears to imprision her again, and its revealed who is her evil brother. With the red ring, Karina defeats Venger and then asks the heroes for the blue ring, Dungeon Master however, does not allow them to give her the blue ring and orders her to leave. The heroes however, had to take her red ring back, for the two rings would open them a path to home. As they arrive in Venger's castle, where Karina is, Sheila confronts Karina and manages to steal the ring from her.
However, when she is about to open their path to home, Sheila hears Karina screaming, imprisioned by Venger. She runs to save her and throws the two rings at Venger: the red ring keeps Venger from moving, while the blue ring is destroyed and turns into a temporary prision for Venger. Its also revealed that Karina's evil personality was an effect of the blue ring, and its gone when its destroyed.
Based on an unfilmed ending for the series, being Venger's sister, she also the child of Dungeon Master and thus also like the pair 1,000 years old.