After defeating the Blood Angel—or, strictly speaking, defeating the Child of Void together with the Blood Angel and resolving the crisis of the Blood Angel's descent in another sense—Iver did not leave Iris immediately.
There was no particular reason for it.
He simply didn't want someone else stealing the credit.
After the Blood Angel descended, he slaughtered all of Iris's Children of the Moon. Although some of them had already transformed into Mist Demons and thus survived, the upper echelons of the "Health Party" controlled by the Children of the Moon had practically been vaporized as well.
Even in Iris, the existence of the Children of the Moon could not be openly acknowledged.
After all, they were monsters that drank human blood. Their existence could never be completely legal anywhere. If their legality were acknowledged, it would amount to acknowledging that humans had become their food.
Therefore, Iris's Children of the Moon had chosen another route. They manipulated the media and controlled the parliament, preventing the news from spreading and using their social influence to control the direction of investigations. This kept their identities as Children of the Moon from being exposed. Even if they were exposed, there would be no hard evidence; and even if there was hard evidence, they could simply deny it as "fake news."
But now, the extinction of the Children of the Moon could not be hidden.
The common people at the Bottom Layer had not noticed what was happening at first... but after so many days, along with the Hourglass's "server-wide announcement," the Blood Angel's death and the extinction of the Children of the Moon could no longer be concealed. Once people realized what had happened, public opinion exploded almost instantly. The news spread throughout the entire Iris Flower Kingdom in practically a single