Colorful

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 knows that he was died (either - 'that he was dead.' or 'that he had died.') 

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

Purapura seems like an angel but he isn't, or at least he said to 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 of the young boy, called Makoto, who had decided to terminate end his previous life on earth. -Just to clarify more what you are talking about. 

But there was a condition, the man had to discover what were the reasons were; why the boy decided to commit suicide. Only if the man discovers those reasons he'll can can he 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 quickly he began to understand the problems surrounding the 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 continues you'll have to watch it.

Nice work here but try and maintain the same time line. You liked to talk as if it was the past and then change to the present and vice versa. But otherwise it is really good.

Colorful

I watched a movie, maybe a 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 knew that he was died dead. 

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 told 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., hHe had to come back to the life, to live thatthe life that a 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 discovered those reasons he'll can could 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 on he began to understand the problems surrounding thatthe 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 continues, you'll have to watch it.