Why are Ringo-chan's cheeks always red?
The Blush Sticker trope is usually used to express childish cheerfulness and/or naivety. In Japan, children are typically depicted with round rosy cheeks.

Ringo is a bit of an airhead, or rather naive, like a child... The Sanada North High Student Council gave her the "childish" nickname "Ringo-chan" for a reason.~



The trope most likely originated from manga where often times it would be easier (and less time consuming) to draw ovals indicating "blushes", rather than shading them in.