It sounds like you’re referring to the light novel / manga series “I Live with the JK (Joshi Kōsei) with the Biggest Boobs in School” (often abbreviated or known in fan circles as “Bocchi JK” or similar ecchi/comedy titles).
Assuming you want a (e.g., a unique aspect, plot device, or recurring element) of the series, here’s one central feature: Feature: “Accidental Coexistence + Extreme Body Contrast Comedy” I Live with the JK with the Biggest Boobs in Sc...
The story’s main hook isn’t just that the female lead has the largest bust in school — it’s how that trait is constantly highlighted through with a male protagonist who is either shy, inexperienced, or easily flustered. It sounds like you’re referring to the light