SPOILER!!!!
Basically the uke in the regular world read this novel that had the name of him and his best friend. After the uke got done reading the novel he was transported into the novel as the charcter in the story. He meets the Seme (His best friend name but not because he a character in the story). The uke wants to change how the story ends because it was a sad ending. The seme died and the uke killed his self after in the story. So since the uke was transported into the story, he wants the save the Seme and have a happy ending so he can go back to his regular world with his friends and family.
@Bloodwyn explains it well in the comment above yours
i am so confused