So she'd punched it into submission? Lukas would have made a Chuck Norris joke, but through experience, he knew that that was a little difficult to express through mime. His expression screwed into one of distant amusement when Lukas dropped the gleam of his bleary eyes onto the instrument once more. He fingered the lifeless strings, plucked at their hopeless sag in a brief spell of wonder. From what he understood, and had read, of string instruments, it was the tension that produced the music.
To express his intentions, Lukas brought a curled fist to his chest, pinky extended. I. His other hand patted his sternum to further the explanation before he reached for the koto and made a rubbing gesture against it's fractures. Like Aladdin with a lamp. That was supposed to show that he intended to fix it, although it might have come across like a DJ scratching records. He pointed to the door, as he would take it with him when he left.
And in case she missed all of that, he signed it out. Whether she knew sign language or not, maybe sake was the key to understanding.