from the way Chen's front is covered in blood, I think she offed somebody, and freaked about it. Maybe that's why she's asking to go back to the old days
The bits highlighted in orange are the lyrics to "you" from Higurashi, so she's probably having a moment like Keiichi does near the end of Onikakushi-hen.
being right next to you...(this is my free imagination like
"Chen was affected by the magical power of the moon. she went berserk, and..."
in Imperishable Night)I will always be smiling next to you.Let's get back to those old days.
This time we can do it well.
