Choi Bak goes by the traditional Mr. Choi, although regulars in Corona Tower call him Bak.

As a porter in the Tower, Bak services the Stamford Suites guests. He wears the standard Corona Tower colors, a cream top with tan trousers, and he is known for the cloth hanging from his back pocket for polishing away fingerprints.

We first meet Choi Bak in Book 1 of The Human-Hybrid Project, Shattered by Glass.