I try to restrain myself and not over-explain when utilizing the text or caption boxes. Especially since the comic isn’t very long at this point. It is a rather insignificant plot point, but Liz cannot hear Yasu’s voice. This detail is mentioned way back on screen 22. I don’t really bring it up again. Yasu can hear Liz. Liz can see Yasu, but she cannot hear him. He’s not corporeal so he can’t really pass her notes. The fourth panel on screen 83 depicts Liz and Yasu learning sign language together.