Loyal and serviceable, and apparently discrete. When she takes out her glasses, she acts somewhat fickle and unconscious.
As Masako clearly said, Renjaku is the only person worthy of her trust. If she wants to discover some information, she relies on Renjaku, and the same story when she must update her busy agenda.
Renjaku was ordered by Masako to keep an eye over Himari. She spies her, videotaping her day to day, and suddenly Himari transforms into the Princess of the crystal, who orders the maid to stop taping her. Renjaku gets afraid and confused with that panorama, wishing to get out of there, while the princess photoshoots her on erotic poses. At the end of that jazz, she is finally ejected from the black panda and she returns to her reality, but she remembers nothing that occured in her meeting with the Princess of the Crystal.