So, I would love if Chii knew the whole time or has recently been made aware through her own powers of observation....but what if she is just saying that so she can get Pickup-senpai to stay away from Yamada considering she knows how he was before?
Although, if Chii didn't know it would be super shocking at this point. Yamada and Ichi are ALWAYS together. They spend so much time with each other...at each other's houses, out and about, on the beach trip (didn't Yamada say not to tell him while they were at the Karaoke place all day?), like there are a TON of hints that if she was unable to see them she would be so dense I would be scared.
Although, if Chii didn't know it would be super shocking at this point. Yamada and Ichi are ALWAYS together. They spend so much time with each other...at each other's houses, out and about, on the beach trip (didn't Yamada say not to tell him while they were at the Karaoke place all day?), like there are a TON of hints that if she was unable to see them she would be so dense I would be scared.