I already guessed that Shiori was the one who saved Hinako back then from car accident. there are several clues: 1). at very earliest chapters, Shiori said that she was "looking for Hinako", why is she searching specifically for her? 2). at previous chapter, it's revealed that after accident, none of the doctors sure how Hinako could survived despite of those severe injuries, and then 3). in this chapter, Ayame said that "that mermaid gives you her blood", just connect those clues together......although I'm not sure why Shiori did that. is that so Hinako will truly believe Shiori in order to fully enjoy her body?