I've seen my share of tsunderes. For a long while I hated them, but then I realised that only the overly violent ones are really annoying, with their violence bordering on abuse... but the mild ones are actually nice...
I'm not sure how you didn't notice the over sensitivity... I mean, she overreacts to a lot of things... she's obviously not very confident. I normally don't mind that... since I have to deal with it often enough, but I guess it's easier once you're invested in the person... Or, who knows, maybe it's something else... I can't put my finger on it, sweet as she is, I think I like Yuri least... (not to say I didn't like her, I still did, just not the most).
Yes, Natsuki is sensitive too, but I just consider that part of her tsundere trait, as opposed to Yuri's stand alone sensitivity.
I wish I could meet Natsuki's papa to give him a piece of my mind... and fist.
I wish we'd have a normal version of this, where we could actually go through with the character stories... it's funny how attached I got to the characters in such a short time, especially since I normally don't like VNs.