Kotou no Serenade

Shoko is a student whose uncle works as a cameraman for the editorial department of a publishing company.
One day she encounters the scene of a bizarre method serial killer. At that time, she and her best friend Asuka become wrapped up in an unthinkable event.

One day the two of them go with cameraman Koji to a deserted island to shoot some footage of a rare hot spring. Although it was supposed to be a fun trip, the seal that has previously been locked on the island is released! A place that intersects with another world, strange changes begining to take place. What is the sad conclusion that awaits these two girls?

[From DLsite English]