Watari-kun's ****** Is about to Collapse

What is Watari-kun's ****** Is about to Collapse?

Naoto Watari lives solely for his little sister, Suzushiro, until his chaotic childhood friend, Satsuki, storms back into his life. Without uttering a single word, her very presence ignites buried memories and unravels his rigid routine. As tensions rise and secrets surface, Naoto’s devotion to Suzushiro clashes with unresolved pain, threatening to collapse his fragile world. (Source: Crunchyroll)