Just who is that chipper young beaver named CJ? We take a deep dive to find out.
CJ is a new character in the Animal Crossing universe. First appearing in New Horizons, CJ replaces Chip as the host of the Fishing Tournament, which happens every third Saturday during certain months (depending on which hemisphere you live in). Since he's replacing Chip, the name CJ is thought to be an abbreviation for "Chip Junior" as it implies CJ is Chip's son. J also uses Chip’s catchphrase of “nyuk, nyuk,” which only strengthens the theory that CJ is Chip’s offspring.
Besides hosting the fishing tourney, CJ shows up on the island every so often just to see if he can find up-and-coming fishing talent and maybe get in a few casts for his live-streams. The apple doesn't all too far from the tree, only, in this case, the apple has a cell phone.
If you spot CJ, he'll offer to purchase your fish for 150% of their value, so it's a good idea to save up your fish to sell to him on his random visits. Keep in mind that CJ won't buy your fish until you've completed a Seasports Challenge, which requires you to catch 3 fish in a row within a specific size range.
Oh, also, CJ is gay. His partner is Flick, the bug-collecting punk Chameleon who runs the Bug Off bug-catching competition. We know this since CJ offers to provide the player with one of Flick's services, which is to build a model of a fish so long as the player can provide three examples of that same fish. During these conversations, CJ refers to Flick as "his partner," implying an adorable cross-species romantic relationship.
This seems to only be the case in the English localization, however. In Japan, CJ refers to Flick as merely his "friend." Japan also doesn’t call him CJ. Instead, he’s named “Justin,” a possible reference to Canadian pop-star Justin Bieber.
If CJ shows up on your island, he’ll stay there for the full day, from 5 AM to 5 AM.
Source: Animal Crossing Fandom Wiki