The 54-year-old, named only as Liao, killed his 57-year-old neighbour before committing suicide Tuesday night in order to have a chess partner after death, Shanghai Daily reported Liao as informing in his suicide note.
The neighbour's body was found by his landlady in Zhejiang province when she visited his room to collect the rent.
Police said they detected evidence of strangulation, and Liao's body in the next room. There also were two notes and some drugs found in that room.
The man was thought to have killed himself over family conflicts and killed his neighbour because he was afraid of being alone after death, his notes suggested.
The landlady described Liao "unsociable and eccentric".