Jigsaw no Machi

Hero works as a private detective. One night while investigating a yakuza case he notices a girl he knows from somewhere. He saw her in a mysterious dream. He feels like his past also changed after the meeting. The Jigsaw puzzle started to collect together. To unveil the secret he needs a month. Hero and that girl shared a dream six years ago. Now hero chooses to live a new life in a dream. And with the last piece of Jigsaw puzzle set in place, a new town appears in front of him.

[From vndbreview]