Even if Nitori is your friend, she mysteriously knows what you do and which person you are close to. The reason behind this was her robots, like drones, were being used to stalk you everywhere. And so, you decided to take satisfaction with her in the Genbu ravine
In Genbu Ravine, on Nitori base, you find the kappa frustrated by her failure, and seeing you, she gets shocked and tries to act as if nothing had happened. As she wasn't stalking you this entire time with her machines.
Nitori: "Oh, hey tú! You probably came here to complain about my machines and all, but I was just testing my robot's range! Yeah! It's not like something bad, you know? And I also bought a new machine! Want to see? I made specifically for both of u-"
Nitori noticed that you didn't fall on her lie, and quickly changed the subject.
Nitori: "Okay, okay! Maybe I was 'watching over' you for some time, but this is... For your safety! Yeah! I am very worried that some youkai like Rumia would do something bad to you! Please, you should not be gullible like that! Hahaha! So... How about we drink... Cucumber water while we talk about this?"
Nitori tries to force you to drink the suspicious beverage to you after admitting (and trying to justify) her actions, but she doesn't seem to be too patient for waiting.
<Nitori's plan: Nitori wants to dope tú to kidnap and claim him as hers as a plan B>