Plot

A high school student discovers one of his classmates, Sakura Yamauchi, is suffering from a terminal illness. This secret brings the two together, as she lives out her final moments.

One day, "Me" - a highschooler - found a paperback in the hospital. The "Disease Coexistence Journal" was its title. It was a diary that "Me"'s classmate, Sakura Yamauchi, had written in secret. Inside, it was written that due to her pancreatic disease, her days were numbered. And thus, "Me" coincidentally went from Just-a-Classmate to a Secret-Knowing-Classmate. It was as if he were being drawn to her, who was his polar opposite. However, the world presented the girl that was already suffering from an illness with an equally cruel reality.

The film begins with haruki. He came to the hospital to cut down his stitches, but suddenly his eyes fell on the diary lying nearby. When he picks it up and opens it, he realizes it's sakura's diary.

The diary was titled living with the Dead, in which Sakura wrote about her pancreatic disease. She was about to die. and at that time, Sakura arrived, and she saw that Haruki had read it all. But Haruki doesn't't have any friends to tell them about Sakura's disease. So it doesn't matter much.

He returns the diary to Sakura and leaves. But Sakura smiles when she sees him. Now in the next scene, we see Haruki going home. Sakura sees him on the way. Seeing this, Haruki changes course. But Sakura smiles and goes after him and tries to talk to him and tells him to keep her illness a secret, to which Haruki says he has no friends.

Sakura says to Haruki I can spend the rest of my life with you, but Haruki tells her to leave, so Sakura laughs and says goodbye

Next week, Sakura becomes a library assistant at the same library where Haruki works. Sakura shows her a diary and tells him that she has made a list of things she wants to do before she dies, and tells Haruki to go with her.

At first, Haruki denies it, but Sakura makes him agree to go with her. After that, we see both of them eating in a restaurant. Sakura asks her why you don't talk to anyone at school. Haruki says that everyone expect his family considers him boring. But Sakura says she is interested in him, and that's why she asked her to come with him. Now they were walking out of the restaurant together.

Sakura then saw a man harrasing the old lady. Now she goes to the man and asks him to apologize to the old lady, but the man grabs her collar. Sakura kicks him and starts running with Haruki.

Now running, they both reached a cafe. Where Sakura asks for haruki's number while talking, but Haruki forbids it. She then tells him that she will be his friend until she dies. And Haruki agreed.

Now when Haruki arrives home, He gets a message from Sakura that she had much fun today, and she asks Haruki to stay with her.

The next day everyone at school was talking about Sakura and Haruki. When Sakura gets there, her best friend Kyoko tells her that Haruki is not a boy of her kind. She says it doesn't matter, they are just friends

Suddenly Kyoko arrives there and tells Sakura to stay away from Haruki, after which she leaves

Then we see them both on the beach, where Sakura tells Haruki that Kyoko is courageous. But if she told her about her illness then whenever she saw her face, she would cry. And in that sense, Haruki should befriend him

On hearing this, Haruki said nothing. Sakura asked her if she would tell anyone about her illness so not everyone will behave normally. But you treat me usually even though you know my reality. So i can tell you everything. And i enjoy hanging out with you

Haruki then asks her if she will die. At which she laughs and says yes. We see them both school, where a boy comes to Haruki and tries to befriend him by giving him bubblegum, but he says nothing.

Now that their school holidays have begun, Haruki and Sakura lie down at home and go out of town together. They both start talking while traveling by train.

Their Sakura asks Haruki his first name. On which he refuses to tell. Because he didn't want Sakura to write his name in her diary, and after her death, Sakura's family came to talk to him. But later, he tells her.

After which we see them both having a lot of fun and shopping. After all this. they stay at the hotel. Sakura goes to the washroom, and Haruki starts reading a book. Sakura yelled and asked Haruki to bring a face wash, but as soon as Haruki opened her bag, he got shocked and put the face wash in the washroom.

When Sakura comes out after taking a bath, they play the game of truth or dare. Sakura chooses truth after Haruki's loss, and Sakura asks him if she likes her. To which Haruki said yes; Sakura gets very shy to hear that.

After which, they both start playing, and they ask each other many questions. Haruki learns a lot about Sakura when Haruki asks her what her happies moment is. She tells him that when she met him, it was her happies moment, Sakura finds Haruki's questions quite dull, so the next time she wins and she asks Haruki to pick him up and take him to bed. Now playing further, Haruki picked up the truth, to which Sakura thought for a moment and asked "What would you do if I said i was afraid of death?" Hearing this, Haruki gets a glimpse of what happend a while ago. He was surprised to see so many medicines in his bag, which is why Haruki chose dare. On which Sakura asks him to come and sleep with her without any arguments. And Haruki has to obey. Now they both fall asleep at night, and the next day Kyoko calls Sakura and asks why she lied in her house that she was going out of town with him.

Sakura apologized. And Kyoko tells her that if Haruki harms her, she'll hit her hard Sakura laughed a lot when she heard that, and after that Kyoko hung up. Then she laughs and tells Haruki what Kyoko says

After which, they both start going back to their city, where Sakura says maybe we should go on a trip again. And as soon as he heard this, he agreed for the first time. And he says he had a lot of fun. Sakura was pleased to hear that. After arriving there, Haruki does not work for several days. And he waits to see her when school opens. Now we see him in school, where Kyoko come to him and says how dare you go with sakura? She looks fearless, but she is very weak at heart.

At the same time, she gets frustrated; if something happends to her, Will you responsibility for it? Kyoko grabs Haruki's coller and tells him to stay away from Sakura.

In the next scene, we see them playing at Sakura's house. Sakura then asks him maybe you will never treat me like a girlfriend, Haruki gets up at prohibition, starts looking for the book, and leaves. Sakura comes from behind, Hugs him, and says I always wanted to do that. Sakura starts kissing Haruki. Seeing this, Haruki began to remember Kyoko's words. Then Sakura stops. And she says it was just a joke.

Haruki then grabs her by the arm while lying on the bed. At first, Sakura forbids him but Sakura starts crying when he doesn't move. Seeing this, Haruki gets frightened and runs away to his house.

On the way, he meets Takahiro; He gets angry with Haruki because he goes to Sakura's house. Now Haruki tries to convince him that there is nothing between us like you think. But takahiro says the whole school is talking about you, which I don't like because I like Sakura. Now hearing that Haruki says that Sakura doesn't like a guy like you who disobeys her, Takahiro gets angry and punches Haruki blood starts to flow from Haruki's nose; Sakura comes looking for Haruki. Seeing he environment there, she starts removing blood from her tissue and angrily tells Takahiro to leave. Haruki tells Sakura that it all happend because of you; Sakura weeps and tells Haroki that it's our destiny. We both met by luck and please stay with me for some more time as my friend. Haruki realizes his mistake and admits it. then Sakura takes him home dresses him, and gives him a book.