Charlie Sato

Charlie Sato was a Warrant Officer who worked in the Vault.

Biography
When Charlie first became a warrant officer for the vault, he was given a tour by Captain Ruth Matheson, and in the vault they came across four objects: An army jacket, a painting, crystal and a wax cylinder, which bore a significance. Each was used in one of the Doctor's many adventures. (AUDIO: Tales from the Vault)

Behind the scenes

 * Both Charlie and the Captain have surnames from Torchwood characters. Ruth has Rex Matheson's surname, and Charlie has Toshiko Sato's.
 * Both Yee Jee Tso and Ruth actress Daphne Ashbrook have played other characters before — Yee played Chang Lee, and Daphne Grace Holloway.