She lost her husband and child during World War II, and nearly died herself when she encountered a young boy who offered her a strange piece of meat. The boy was Masato, and the meat was mermaid flesh. Initially, Misa was delighted to have a new child in her life, but she grew fearful as neither of them aged, becoming terrified of Masato's abilities. Five years ago, she fled from him and was taken in by an elderly man whom she later married.
About a month ago, they were involved in a boating accident, and Misa was presumed dead until she reappeared a week later without any injuries. Masato found her and compelled her to continue acting as his mother figure. In an attempt to stop him from feeding anyone else the mermaid flesh, Misa tried to take it from him, but she failed. Unfortunately, she did not become fully immortal; the effects of the mermaid flesh began to wear off, and her healing powers weakened.
Masato simply told her he would find a replacement. Eventually, Misa was killed by a Lost Soul, formerly Masato’s nanny, Yukie. Masato shed a tear for her death before leaving.
