K no Souretsu 1-2

Funeral bells are ringing the day Mikaya moves into a new apartment. Once he arrives, he learns a startling fact; his flat was previously occupied by the dead man, K. Strangely enough, no one ever found K's body...yet all the people who lived in the same apartment complex as him are absolutely convinced of his death. Where is the body, and could it be one of his eccentric neighbours who was responsible for K's death and subsequent disappearance?