One time I read a shoujo manga that was just one chapter. I don't remember if it was included as an extra in another manga or if it was manga of a manga that was a collection of stories, but I do remember that this one story was just one chapter. Some things about it that I remember
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• It wasn't a romance like most shoujo manga are, this one was about friendship between two girls
• There were two female leads. One had long light hair and didn't wear glasses and I think she was the protagonist. The other had shorter, dark hair and wore glasses.
• I remember that the two of them weren't exactly friends at some point and the girl with light hair used to ignore the one with dark hair and glasses and they had kind of a broken relationship, but I think they actually both wanted to be friends, and somehow just couldn't say it
• The one with long light hair, I think she takes a train or a bus at night and there is only one other person in the train/bus, and it's the other girl, the glasses girl.
• I think the bus stops somewhere and the two girls get off there but just for a moment and they talk and make peace with each other and have closure about their friendship.
• When the one with long light hair gets on the bus again because that wasn't actually her stop, I think the one with glasses doesn't go with her and she says she's staying and says goodbye.
• I don't remember how the story tells the reader about this but the girl with glasses had died. She was dead, and that bus probably took her to the "other side".
• I think the cover of this manga/one-shot shows the two girls together
  . I really wish I could remember the name of this manga/one-shot/single chapter. If you know anything like this, please, please give me a helping hand?

Edit: I found it, it's Saitee no Kimi wo Wasurenai