She's Nathan's pet cat and visible Guardian. Nathan calls her Tsubasa.
Her "feral" form has a permanent case of kitty-resting-bitch-face.

She works in the same building as Zeta and Marlin, with the latter being her personal assistant.

Bie is a very proper, confident and decisive lady, she wants to make sure that everything is done correctly at all times.
She is very serious and committed to her job.