|Eye color||Black; when opened/closed|
|Relationship||Numbuh 4 (crush; in love with; future husband), Numbuh 1 (sometimes)|
|Family||Genki Sanban (mother), Kani Sanban (father), Mushi Sanban (younger sister)|
|Friends||Numbuh 1, Numbuh 2, Numbuh 4, Numbuh 5, Numbuh 23, Numbuh 86 (sometimes), Numbuh 362|
|Enemies||Villains, King Sandy, Chester, Chad|
|Nicknames||None; other than her codename, which called by mostly everyone|
|Voiced by||Lauren Tom|
"Don't you ever, ever call Rainbow Monkeys "stupid"!"
Kuki Sanban a.k.a. Numbuh 3 is a happy-go-lucky, 10-year-old Japanese girl who is in charge of Diversionary Tactics and is Medical Specialist of Sector V. She is the youngest operative, and one of the two female members (alongside Numbuh 5) in her sector.
Numbuh 3's usual outfit is an over-sized green shirt, black leggings, green socks, and black and white chucks. She has long black hair with bangs. Her eyes are very thin, almost appearing closed most of the time, although she does open them wider on occasion. She has more alternative costumes than any other characters in the show.
Numbuh 3 is described as the "Diversionary Tactics Expert", nurse of medic lab and hamsters' caretaker of Sector V, with a very short attention span, but long on charm, speaking in a slight Asian accent, and often alludes to her being Japanese. She is girly, optimistic, bubbly, dizzy-headed, clueless, kind, caring, patient, gentle, and arguably smarter than her teammate, Numbuh 4, upon whom she harbors a crush, as seen throughout the show.
She loves Rainbow Monkeys, which she collects, fantasizes about, and has extensive knowledge about. Due to her great love for Rainbow Monkeys, she will often irrationally defend them, occasionally allowing her insanely aggressive side to show (generally accompanied by her face turning red, teeth and ears becoming pointed and eyes flaming, resembling an oni, a Japanese demon). Despite being generally good natured, she will occasionally have similar explosive tantrums when she is ignored or doesn't get what she wants. As shown when the macaroni Rainbow Monkey painting is accidentally shattered by Numbuh 13 in Operation: M.A.C.A.R.R.O.N.I., she has the ability to scream at a deafening volume.
She is usually seen with a Rainbow Monkey doll, and her room in Sector V's Treehouse is filled with various stuffed animals and anything else colorful and fuzzy. A special ability of Numbuh 3's is that she can smell and sense Rainbow Monkeys with her nose and her heart as stated in Operation: R.A.I.N.B.O.W.S. and Operation: S.A.T.U.R.N.. She seems to also have a capability of speaking languages that would normally be dubbed gibberish or non-understandable, shown in Operation: D.I.A.P.E.R. and Operation: V.I.D.E.O.G.A.M.E. (Baby and Firefly, respectively).
She is the pilot of Hippy-Hop, a giant mechanical rabbit that is equipped with a complete arsenal of weapons such as missiles and drills, with a running gag throughout the show that Hippy-Hop gets destroyed whenever it appears. Despite her attitude, Numbuh 3 shows her intelligence in a few episodes, such in Operation: H.O.L.I.D.A.Y., when it is apparent that she can pilot an airplane. In Operation: H.O.M.E., it was revealed that she had a Rainbow Monkey called My First Rainbow Monkey. Also, in Operation: L.I.C.E. she had a stuffed animal named Mr. Mopsey.
Like Numbuh 5, Numbuh 3 also has a motherly side, as shown in Operation: C.A.M.P.. In this episode, she and Numbuh 2 take care of a skunk named Bradley, referring to the skunk as her baby. She often worries over Bradley and does whatever it takes to make sure that he is safe. Another example of her motherly side was shown in Operation: C.A.K.E.D.-T.H.R.E.E., when she helped Numbuh 1 take care of the baby chicks that had hatched.
1. Green Shirt (Main Outfit)
2. Nurse outfit
3. Pink party dress
4. Space outfit
5. Rainbow Monkey costume
6. Halloween costume
8. Party dress
9. Red and White outfit (From Operation: C.A.B.L.E.T.V.)
10. School play outfit
11. Three Swimsuits (Green, Purple, and Pink)
12. Investigator outfit
- Her most prized characteristic, according to Operation: C.A.R.A.M.E.L., is her cheerfulness, which is too sweet.
- Her favorite type of Rainbow Monkey is an orange one, referencing her crush on Wally, specifically his orange sweater.
- Her favorite snack is popcorn, as shown in Operation: S.L.U.M.B.E.R. and Operation: P.L.A.N.E.T.
- Sometimes, when she's really angry, she pulls Numbuh 4 by the shirt.
- Her codename is linked to her last name "Sanban", since san (三) means three and ban (番) means number in Japanese.
- Her stuffed animals have the number 3 painted on them.
- She is the 23rd person to steal Grim's scythe, even though she technically had it given to her.
- The only time she got to lead a mission was Operation: F.A.S.T.-F.O.O.D. which resulted in her kidnapping for a majority of the mission.
- She was temporarily Sector V's leader in Operation: F.E.R.A.L.
- It is revealed that she is not as 'air-headed' as she leads everyone to believe, as seen in Operation: I.N.T.E.R.V.I.E.W.S., when Numbuh 1 is leaving and she asks him what they are doing in the next days, to which he replies that he won't be there, and she says, "Oh, I know you're leaving, silly. What do you think I am, an airhead or something?"
- It is hinted that Numbuh 3 may be the one to create the acronyms for the missions and weapons as seen in The Grim Adventures of the KND, when the M.A.N.D.R.O.B.O.T. has a stupid acronym and Mandy asks Numbuh 3, "What kind of acronyom is that?!", to which she replies, "Well, if you weren't in such a rush, I could've come up with a better one!"
- There is a running joke with Numbuh 3 is that, whenever ejecting from Hippy-Hop, her parachute always comes out after she's already hit the ground.
- Operation: H.O.T.S.T.U.F.F. hints that Kuki has some sort of supernatural power over fire simular to Father and Grandfather's abilities. It should also be noted that Numbuh 3's powers seem to be stronger than the latter's. Her powers may also be one of the reasons that Mr. Sanban keeps the house so cold.
- Numbuh 3, along with Numbuh 5 are the only Sector V operatives who have never met Vin Moosk, Windsor, and Froggy McDougal, due to them obviously not appearing in Operation: K.N.O.T.