Responses
I think he just happened to be their friend. He did mention that Enomoto died by accident and as a friend he couldn't allow it so he held onto his soul. As for knowing the outcome, Haruna knew both Enomoto and Hagino well. So he knew they'd resolve their misunderstanding through this ordeal.
ngl i got kind of confused with harunas identity towards the end, like i understand he only erased the fact that he was an angel, but when he said he knew what the outcome of this would be i was like.. like how much does he know and like was he their friend organically and just happened to be an angel, or was he sent their for the purpose of protecting them and guarding them