I raise you "Sugar Baby Love," the opening theme from Little Snow Fairy Sugar. It doesn't get any cuter than this:
In keeping with ultimate cuteness, the central story is about how middle-schooler Saga completes grieving for her mother even as her snow fairy friends become full-fledged snow fairies by finding their "twinkles." I can tell you right now that the show never ever tells you what a twinkle is. But nonetheless you know what it is when the show is over.
I'm guessing that onechan might well get into the waffos (waffles) and maybe the bubble baths, but twinkles are probably a bit sophisticated for her.
On a completely different tip, here's a mashup that combines the opening music* and visual styling for Cowboy Bebop with the characters from Azumanga Daioh:
*By the fiercely talented by Yoko Kanno, who's also done the music for the Ghost in the Shell franchise.
Here's a somewhat different take on Azumanga Daioh:
The little cute one is Chiyochan, a genius who went from 6th grade to high school. In the middle of that video you see a sequence where the girls are at the beach and one of them, Sakaki, daydreams that she's riding a dolphin. That is a very clever little piece of film-making, though it loses something without the dialog.