Responses
I think Sei know about hidden camera since he notice there's a camera in there room. That was when they have a misunderstanding. He mentioned it to Kanao but he didn't answer why there's a camera in their room. Kanao is the one who set-up the camera.
Also Sei let him meet Kanai so that he would finally leave them alone
KAORU*!
I get kanao and the perverted neighbor but when did kaoru and sei meet? why let kaoru meet the neighbor? Since when did sei know about the cameras and everything? Im so confuse.