As Janken got cut off - rather brutally - from explaining details, the keen eye could've observed, for a mere instant, the curious glimmer fade from Nathan's sight. The moment was short, however, and some would've probably pinned the observation onto their imagination.
Still, as short as the answers were, they were indeed answers. Instead of mulling over the unexplained specifics, Nathan concentrated on the ongoing... startup? procedures, albeit clearly suppressing both Aura and awareness when the IV went in. The phantom hand he was distinctly feeling on his forehead after Grace's passage helped in that regard.
When Jane passed afterwards, Nathan rapidly realized that the lack of changing distance as she pulled her hand away, coupled with the lack of proprioception that would indicate he was in the process of standing up, meant his soul was being guided out of its usual dwelling. He quickly got to work on observing his, well, soul - it looked pretty much exactly like the person lying behind him, but blurrier. There was a slight brightness to the surfaces of his astral body, as well, as if they glowed faintly from within. Must've been due to his usually-white Aura colour. As he took... a piece of his soul? off his back, he observed Ergia's misty form, every movement he was making sending ants coursing through nonexistant nerves. He mentally formulated the hypothesis that it was his mind reflexively relaying the complete lack of sensory feedback from his body like this, until it adapted anyway.
He looked up from Ergia's compact form, the experiment's... executors? as they gave further instructions, amongst which Grace did so from within his mind. Felt like having another train of thought running in parallel to the usual conscious one, oddly enough.
He walked towards and into the Room when Jane held its door open, keenly aware that this was, in a way, his first out-of-body experience. He wasn't exactly sure how his semblance would work out, but hopefully Janken would give him no need to test it.
Although he really wanted to test it.