[ The question catches him off-guard, though after a moment, he realizes it shouldn't be all that surprising. Nanami has always been far more perceptive than he lets on, far more empathetic and thoughtful, so that he had intuited the true nature of his relationship with Sumina is no surprising. Hell, even if he hadn't put together that they were involved, it's apparent that they care about each other a lot. He has other friends here he'll need to stay farewell to, but none of them will be impacted as much as Sumina will.

He presses his lips together before blowing a thin sigh out between them. ]

...She's always known I'd have to go back someday, too. [ But like him, she likely wouldn't have expected it so soon, so suddenly. It's better this way, though, he thinks. His unfinished business has been a roadblock in so many ways in his life, and if he goes back to finish it...it'd be better, in the long run. ] She'll understand.

[ A beat, his gaze finding some idle corner of the room, before he adds: ]

She's a lot like you, you know. She'll work herself to death before reflecting on her own needs.

[ And she probably will when he goes, too. ]