Shinsekai no ko to, o-tomari dakara de na... tte sa. "Because it’s an overnight stay with the New World’s child, so... y'know."
Given this, if I were to create a text based on a possible interpretation: shinseki no ko to o tomari dakara de na tesa
To understand why this phrase resonates, we have to look at the individual components of the sentence: Shinsekai no ko to, o-tomari dakara de na
Possible interpretations based on similar-sounding Japanese phrases: Shinsekai no ko to
The story centers on characters living together, focusing on deepening bonds and developing emotions.
Alternatively, are you trying to write:
新石の子と留守だからでなー、とさ