
That kid probably died. I think the chances of him seeing someone's death is slim so it struck him. But you know, if you are meant to die, that's meant to happen. He couldn't have prevented that for all he can. He also kept on checking the kid's future so it meant to traumatise him either way.
The senpai is fine. I felt like the ML is not part of it for the most part. The others have sudden misfortune like out of nowhere, it might be coincidences but he could only blame himself.
But the senpai, he only talks to him briefly and the girl is not his liability. The senpai also felt alarm bells before that so it could have been prevented. He's also not close to him, only felt indebted because he looks like Koyama.
I'm trying to tell is, it only became part of the story because the senpai looks like Koyama (out of all the people he caused misfortune) it also opens up the fate to meet MC so I think it's meant to happen and lastly the girl suspect is arrested and he's not solely to blame for that.
The uke's first who went missing and seme's senpai, those two still needs some conclusion for me....I can't close this story without information of those two.