[He recognizes that tone - it's the same protective way Kotone also sounded when he told her about happened, the same way his other friends are more concerned than curious for him.

Ryoji really is surrounded by good people, he thinks warmly. But he doesn't want them to commit murder just for him.]

It's okay, Aether-san. He already paid for it...I killed him.

[He has yet to admit that to someone outside of Minato and Kotone.]

He was in the vicinity when I lost control, after all. So you don't need to make him pay anymore.