A: なんでそんなに眠そう？ B: 親戚の子とお泊まりだったんだ。全然寝られなかったよ。

In both cases, “da kara” justifies the speaker’s refusal or tiredness. It’s a polite (and sometimes exasperated) explanation. “Shinseki no ko to o tomari da kara” may seem like a random string of words, but for anyone who has cared for a young relative overnight, it’s a familiar sigh of responsibility, love, and exhaustion. The “eng free” part reminds us that family life happens across languages — and English speakers deserve to understand it too.

A: Want to go for a drink? B: Can’t today. Because I’m staying overnight with a relative’s child. And tomorrow’s early.