The developers describe the content like this:
This Game may contain content not appropriate for all ages, or may not be appropriate for viewing at work: Frequent Violence or Gore, General Mature Content
Nestled in the heart of Tokyo, the quaint little aquarium, Manten Aquarium.
Numerous urban legends have arisen from here.
On the night of the full moon the waters turn to blood and man faced fish lurk within.
Junior high school students Mayu and Himeno came to Manten Aquarium to investigate these urban legends.
In the beginning it was fun, but then.
They see a glimpse of Mayu’s missing littler sister, Mari.
The wheels of fate begin turning as they chase after Mari’s shadow.
--Before she realizes it, Mayu finds herself alone and lost in the crimson aquarium.
How to play
・Proceed through the story from Mayu’s point of view
・Make choices through the game and choose your fate.
・3 main story routes
・Over 30 endings (Mostly bad)