They met on the last hot day of August, when the cicadas screamed like a single frantic voice and the sun seemed unwilling to set. Haru carried a battered camcorder he’d found at a flea market; Natsu carried curiosity the size of a thunderhead. Both were seventeen, both too aware that something in their town—its age, its people, their own futures—was shifting like heat above asphalt.
There is a specific kind of silence that exists only in late August. It is not the silence of emptiness, but the silence of holding one’s breath. It is the sound of a ceiling fan slicing through humid air, counting down the revolutions of a season that refused to end.
Themes and Character Development
Until Summer Ends (Natsu ga Owaranai made) - There isn't a widely recognized anime by this exact title. It's possible you're thinking of a lesser-known series, a movie, or perhaps a novel/light novel.
Searches for "the animation full" are not accidental. Here is why dedicated fans avoid clips or compilations: