I watched a movie, maybe half year ago, which story is about a man who is reincarnated in a young boy's body who has just died recently .The main character doesn't remember anything, he just know that he was died

In the heaven ( It's looks like a train station) He met a boy who will be his guide, a young boy called Purapura.

Purapura seems like an angel but he isn't, or at least, he said him that he isn't an angel but a worker from there.
Purapura said to the man that he had won an award, "the opportunity to live a new life in another body".

The man didn't understand anything but, he had no choice, he had to come back to the life, to live that life that young boy, called Makoto, had decided to terminate.

But there was a condition, the man had to discover what were the reasons why the boy decided to commit suicide, only if the man discover those reasons he'll can remain in the world with this body.

Suddenly he woke up in an hospital surrounded by people who he had never seen before, they were, of course,his family.

At first, the life in his new body was strange, he didn't know how he should act in front of his new family, and he acted, for some time, like a good boy, but early he began to understand the problems surrounding that boy who commited suicide and he got angry with them.

I could tell you more about that film but I don't want to spoil the movie so,If you want to know how the story continue you'll have to watch it.