Decaying Camellia Petals

(TW: Story may contain sensitive topics such as, suicide, depression, mental illness, and perhaps others. Gruesome and/or heavily described gore. Please do not read if you are disturbed or uncomfortable by any of these.)

Two boys, Osamu Dazai and Chuuya Nakahara, sophomores in high school.
The two have been friends for a while now, they often fight and bicker at each other any chance they get.

...

But...
Dazai has been acting strangely weird lately, he tends to zone out more and distances himself from others, and even Chuuya, which somewhat worries Chuuya.
Chuuya knows Dazai has been suicidal for a while, but he's starting to think it's becoming a serious issue, more than it was before.
Chuuya plans to help Dazai get through his issues and get him help, and hopefully get Dazai back to his old self.

But even that, is a hard thing to achieve.

(Age 15.)

[This could possibly be taken as platonic or romantic Soukoku, although the romantic ship itself is not the point of the story.]