Can someone help me?. Im looking for a bl manga... that happened in the train station.. T...

Can someone help me?. Im looking for a bl manga... that happened in the train station..

There was this student that was sick in the train and was saved by another guy, who is another student from another school...

the only thing that he remembers is a keychain attached to the guy's bag (or phone?),...

He kept on looking for the guy to say thanks and discovered that the guy his looking for looks like a deliquent..

Thanks