The appeal of the "tsundere childhood friend becomes hot" trope lies in the history between the characters. Unlike a new love interest, she has years of shared memories with the protagonist. When she adds "physical bombshell" to her list of traits, the dynamic shifts from "sibling-like bickering" to "intense romantic tension."
The "celica magia tsundere childhood friend becomes hot" trope can be seen in various anime and manga series. Some notable examples include: