The Numbuh 3-Numbuh 4 Relationship is the most obvious, and perhaps the strongest, romantic relationship in the show Codename: Kids Next Door. While Numbuh 3 does have a crush on Numbuh 4, his greater love for her is exemplified in more episodes, including Operation: B.E.A.C.H.. However, the two express their crush in very unlike ways: Numbuh 3 is very kind to Numbuh 4, while he tries to act cool and talks a bit rudely to her. This difference, though, shows that they are attracted to their opposite traits.
Evidence of their crush:
* Numbuh 4 acts jealous towards other boys who flirt with Numbuh 3, including Ace "The Kid" (Operation: C.A.K.E