He can't be too obvious about it. No goodbye, it's been an honor to know you or anything like that. Akechi wouldn't have gotten it back home, but there's a good chance that here, he'd figure out what that meant. So Ren chooses his words carefully.

"I know what people say about you here." His face darkens; but only for a second, before he goes back to looking oddly distant. "But it's bullshit. You're clever and determined, and you're really... I know I've been..." He struggles briefly to find the right words. "Thanks. For looking out for me. You're a good friend."