Evergreen December

Sixteen years had passed after the car accident. Hiratoshi, now a grown man and the best detective of Ishida Police Department continued to perceive dreams of a mysterious girl among a bush of roses. There was a fragment of his past that he had forever lost and he would do anything to get it back. The only remainder of that memory was a silver key he had ever since his childhood which he had no idea about its origin.
After desperately trying to chase a criminal, he got shot and was given a leave from his work as a detective. He took his leave back in his hometown, Kawagami where the four seasons reigned. But his arrival had somehow bewildered the people, for autumn and winter never came.