Rean likes Yuuki a lot! She's cute, fun, easy to talk to, and in general he doesn't feel like he has to rein in parts of himself he'd usually be a little embarrassed to talk about because fellow nerd friend!!

At the same time, though, he has the same problem with Yuuki as he does a lot of his slightly more distant CR: he feels obligated to be the composed "leader" type, which means he's absolutely unwilling to show any real weakness around her ever because he's convinced doing so will mean people will think less of him.

So, basically: happy funtime friend! But also, intentionally keeping her at arm's length because Rean's a problem child.