"That night Konishikawa died of acute alcohol poisoning. Police investigation found his co-worker's fingerprints were on a bottle in the same room he was found dead"
I'm with the other women. Misato-san should have gotten together with Shimizu-san. Or at least someone around her own age, and preferably not a co-worker. And now she's forced her way into the room of her obviously drunk manager. Bad decisions all round.
I hate to break this to you, but people can't control who they have feelings for. People pass up more convenient relationships in favor of problematic ones all the time, even if it's a burden, because at the end of the day, the heart wants what the heart wants.