Harvey was found impaled on an object in the mansion, his lower body missing.
Who had brutally murdered him? In the midst of the storm, a sound like singing echoed. It reminded everyone of the "Siren," the fairytale creature that Harvey had been pursuing, and they all held their breath. At the same time, Luciola was found unconscious. When
Luciola woke up, she told Sakuya and the others about the attack and said it was the work of a Siren.
After hearing Luciola's story, Sakuya noticed something strange.

In search of clues to the case, Sakuya enters Eliseo's studio with Shardina.
All they find is Eliseo's diary. It contains details about Eliseo before he became a painter, and, surprisingly, a secret related to his immortal body.
As the time limit set by Shardina approaches, Sakuya slowly gets closer to the truth.
The series of incidents are deeply connected to events in Eliseo's past.
The perpetrator of the inexplicable serial murders is...