Problem parsing this sentence, particle (postposition) の > ( My trouble lies with > If I consider to act as adverbial form of , then I don't know what is modified by : taking to work in attributive role modifies nouns, and there is no noun here; taking to work as an agent case marker doesn't make sense to me, as there is nothing for to act upon. Taking as a noun doesn't make sense either because it's missing a case marker, something like > **** with in allative role) **In other words, how does work here?** A bit more if necessary for context:

That is not an adverb but two nouns of and .

The functions as the possessive marker for the , in other words stands for deep inside the abdomen. The here is a noun (like that means a deep part and the relation between is 'equivalent'.

In this example, those nouns are used like an adverb by their own, but if you add , it should be .