About japanese special expressions noren ni udeoshi not worth doing waste of effort saishokukenbi being gifted with both intelligence and beauty hakuchūdōdō openly (unashamedly) in broad daylight koshitantan vigilantly with an opportunity to prey upon with an eagle eye Is there a site or list or something where one can find expressions like these? Also roughly how many are of these kind of expressions?

Except the first, those words are called {}. Some of those originate from Chinese idioms. Others are simple compositions of two usually 2-character words. Since their origin is mostly Chinese, they are usually read as Onyomi (that's why the first word doesn't fall in this category).

There exist several online dictionaries for these , e.g. on < I was able to find . The sheer amount suggests however to not learn them all like a simple vocabulary list. I'd suggest to learn them after witnessing native speakers using them.