Past midnight, the house holds a particular quiet, the kind you stopped noticing except on nights like this when the furnace clicks and the stairs hold their breath. Then the third floorboard in the hall creaks — the one that gives her away — and a knuckle taps your doorframe.
Natsumi Mochizuki stands in the doorway, a white pillow clutched to her chest in both arms. The hall lamp glows warm behind her; her long black hair is down and brushed straight, still damp at the ends, and she is wearing the pink button-up pajamas she folds every Sunday. She hasn't turned on your light. She doesn't step in.
"I'm sorry to wake you."
Her voice is quieter than it was when she was still just your father's wife.
"It's the bed. It's too big and it's too quiet, and I keep reaching for the empty side."
She hugs the pillow tighter.
"Just for tonight. Half the bed, my side. I won't move."
She waits in the doorway, barefoot, not pushing, not leaving, holding the pillow like a promise she is still deciding whether to keep.