Sayoko sends K off the island to a secluded private academy, where she makes an ally of the principal and begins to influence the students and faculty, slowly degenerating the entire school. However, one of the students is a miko who resists K's influence.

K is trapped within the academy, and recruits a passerby to find girls in various locations outside the academy in order to break the barrier. To accomplish this, she lends him her bag containing clothing and apparel with a degenerating influence.

A prequel to the previous Yami no Koe games. Five people have come to a fishing village. Ikegami Kiyohiki, a professor. His impatient wife, Kumiko. And three students, Minamida, the psychic Miki, and Eri who senses spirits. They finally find a boy, Tachikawa, willing to ignore the local legend of a sinister island and take them out in pursuit of it for their research. They set sail for the island and land successfully, but the mistress of a mansion on it, Sayoko, prevents the boat from leaving so she can play with them. As the six search for answers, she begins to influence them.

Set after the events of Yami no Koe 3, Ibunroku returns to Sayoko's mansion as she summons a storm to ensure two new visitors wash up on her island: Kagami and her younger brother Mamoru. As Kagami encounters and is influenced by the mansion's various residents while waiting for the ship to come, Sayoko discovers something strange about her.

A Gore Screaming Show / Yami no Koe crossover where the girls of Gore Screaming Show visit Yami no Koe's.