Invisible Sign: Isu

Fifteen years ago main character's older brother Rin got kidnapped. As a result mother went mad and father lost interest in life, so family's private psychiatrist had to care of the young Shun. The boy starts to attend school with his only friend but a dreadful murder of student occurs there one day. Shun starts to see visions of the killed student and nightmares where some man wants to catch him. Overcome with fear, he occasionally loses control over his consciousness.
A police investigator finds a lot of similarities of this murder with the case fifteen years ago. People around Shun get involved in the investigation, including a classmate girl with the same name as his disappeared brother.
Will the mystery be revealed?