Aka to Teketeke

Mami Kusanagi and her two friends, Masako and Kayo, worked together at the Cast Dream company.

One day Kayo was found slaughtered.
On her cell phone, in red text, it said...
aka aka aka aka
aka aka aka aka
aka aka aka aka
aka aka aka aka...

There's an urban legend about this message. It's received by victims just before their grisly murders. And now, it's appearing on Masako and Mami's cell phones, too...

[from DLsite]