Expecting to be alone with はず

Grammar Explanation: Expectation with はず

After Chino shows Cocoa to the changing room, Chino goes to get Cocoa’s uniform. Left alone, Cocoa gets a feeling otherwise.

ココア:: 「誰(だれ)もいないはずなのに誰(だれ)かに見(み)られているような」; "Even though I'm sure there isn't anyone (here), I feel like I'm being watched by someone."

Note the presence of なのに.