Kaidan to Odorou, Soshite Anata wa Kaidan de Odoru

The story is set in a middle school in Shishibone city. Tomohiro Miyajima, the main character of the story, and his group of friends are busy studying for an exam. One day, in search for a thrilling mystery as well as easy money, they take several donation boxes and fabricate a curse to scare everyone: "Ohone-sama's curse". After scrawling 骨 (bone) all over the chalkboards and spreading rumors of the curse, the donation boxes are quickly filled and the curse becomes a major legend of the school. Of course, only Tomohiro and his friends knew the curse was fake. It wasn't possible for anything to happen. That is, until they receive a donation of 50,000 yen and a letter to go with it, reading: "Please curse Tanashi Miyoko" Immediately after that letter, bullying and crimes in the school escalated, strange incidents occur, and Tomohiro and his friends are left with a much bigger mystery than they wanted to have, that they are forced to investigate by themselves. What happened shouldn't have happened. Those who are alive should not be alive, those who know what they know shouldn't have been able to know, and familiar faces are hardly what they seem, but why? And how? Source: Manga Updates