Mrs. Uno is the mother of Nigel and wife of Monty. She is also a jolly British-American lady.
In the series finale, Operation: I.N.T.E.R.V.I.E.W.S., it is revealed that she was once Numbuh 999, the first female operative in the modern Kids Next Door Organization.
Her voice was first heard in Operation: C.A.N.N.O.N., calling Numbuh 1 to start their trip to Hap-Happy Land.
She was physically seen for the first time, although only from the waist down, in Operation: K.N.O.T. where she is seen doing a crossword puzzle while her son wrestles with a necktie.
Mrs. Uno accompanied Numbuh 1 to the doctor's office in Operation: S.A.F.A.R.I. to make sure he got his moosebump shots, which turned out to be operated by Chester.
She did not join her husband and son on their trip to England in Operation: E.N.G.L.A.N.D.
At the end of Operation: I.N.T.E.R.V.I.E.W.S., she and Monty were recommissioned in order to properly say goodbye to their son before he was sent out to represent Earth in the Galactic KND.