-nekopoi--natsu-ga-owaru-made---natsu-no-owari-...

The Japanese concept of mono no aware —an empathy toward things and the awareness of impermanence—is central here. Visual markers like the changing sound of cicadas, longer shadows, and the cooling evening air serve as symbols for the loss of innocence.

The keyword you've encountered specifically points to the 2024 sequel, which completes the story. -NekoPoi--Natsu-ga-Owaru-made---Natsu-no-Owari-...