Mailbox at 3:13 Am

My sister is dead. Police said she died in the early morning of May 13. But it took three days before anyone called the police about her disappearance. She died in a palm forest 900 meters in front of her home and hung there for 104 days without anyone noticing. The closing sheet read: Traffic accident death. But my sister doesn't have a car and can't even ride a bicycle. That night, she went out wearing slippers. Three days after she disappeared, the police sergeant on duty called: We have contacted Mei Feng, but she doesn't want you to know where she is. There is no recording, no record, just "safety confirmed." We believed it. Until 3:13 in the morning that day, the old mailbox of the abandoned grocery store next to the palm forest rang. There was a letter lying in the mailbox, signed May 12th, in my sister's handwriting. She asked me: If I disappear one day, will anyone look for me? I wrote back: I will, I have been looking for it. And she survived. In another timeline, she lived until dawn. But the price is that some people begin to disappear from this world. Later I learned that all the people on this island who had been "confirmed safe" were writing to the same mailbox. And I am the only one who can reply.