I'm a bit confused by this chapter. She claims the old man killed his daughter, but the old man says it wasnt his child.
Minoru also saw a younger version of himself in the bamboo, and they said the little girls bones were found close to him.
Ok i re-read and I think this is whats going on: The old ghost isn't the man who recently died, but the old man from the Meiji period whose daughter was 'found' 1 year later in the closet.
I think the old man ghost murdered the child, and they found a replacement for the girl and kept her from prying eyes (until she was married) so they couldn't say it wasnt her.
Harumi disappeared because she was murdered by Minoru out of jealousy.