Ohara, Kuon
Kuon Ohara is Rinne’s mother, a shut-in always covering herself with a hood; she also communicates with a note decorated with a heart mark.
Kuon was a shut-in and always communicated with Setsuna by writing letters instead of talking. She can’t go outside because of a syndrome which will kill her if she exposes herself to sunlight for even a little while.
Kuon lied about the syndrome to keep herself away from Setsuna, so that he wouldn’t learn about her true identity.