The phrase "Shinseki no ko to o tomari da kara" (親戚の子とお泊まりだから) roughly translates to Because I’m staying overnight with a relative’s child
It signals:
Linguists call this or "caretaker speech." When speaking to a young relative, you naturally: shinseki no ko to o tomari da kara eng better
The "stayover" ( otomari ) trope is the central driver, creating a forced proximity that shifts the dynamic from casual family acquaintance to something more intense. The phrase "Shinseki no ko to o tomari