Ohitorisama I think has what you're looking for to a good degree, even if it's not totally the same as a reversed Itazura or Nodame and it's "noona" too which you didn't ask for.
The guy is more active, playful, clumsy, positive towards almost naivety sometimes (but not stupid), a little shy, while she is -for the most part- self-confident, more mature, totally independent, professional and more cold in comparison. In a good amount of episodes, more than half of them I'd say she's really cold, and even though this changes a little, even then there's a big difference between them in this regard.
I liked the dynamic a lot! Even though the guy was almost a bit too immature at first ;) But other than other noona romances where age almost makes no difference and it's still more like a classic romance, this REALLY is different.
I'm also very much interested in what you said you're looking for in this thread ;)