Nanami focuses on the shower as well, though he's especially aware of how turned on Haibara got him before asking that question. If Yu hadn't, they very well probably would have finished in the shower. He mostly towels his hair dry and brushes it out before he exits the bathroom a moment after Yu.

"Underneath," Nanami smiles, "I want to drive you to bliss."

He has only thought about it the whole time since they focused on showering.