Rebecca

Rebecca is a skeleton. She wears a black, slightly torn jacket with purple checkered sleeves and green fur. Under her eye sockets, Rebecca has green streaks of makeup resembling tears.

Rebecca may seem rude or indifferent at first, but in reality, Rebecca loves communication, is simply very appreciative of her work, and does not like being distracted or when someone is talking nonsense.

Tunas are living cartoons made of ichor (including Rebecca)
Ichor is the black, viscous liquid from which all tuns were created. Ichor itself is poisonous to humans, so it was stored in capsules; tuns are immune to it, as it's what they're made of.
Maines are the main characters. Each event toon has its own main. For Christmas toons, it's Bobet (a Christmas ball), for Easter toons, it's Bessie (a wicker basket of flowers), and for Halloween toons, it's Gordy (an anthropomorphic pumpkin).
The name of the children's show from Where All the Tunes Appeared is "The World of Dandy" or "Gardeview".
Children often come to Gardeview, because this building is often used not only as an animation studio, but also as an entertainment center for children, and maybe even as a kindergarten. In general, children often run around Gardeview with their favorite cartoon characters.