Existing theoretical frameworks on so-called negative polarity items so far have not offered an adequate enough description of their variety. We use corpus data of modern Japanese to advance in the description of semantics and pragmatics of adverb intensifiers within this group. The method that is being used for this is twofold. First we undertake separate semantic analysis of each item, recurring to diachronic factors if relevant. In this way we can subdivide the eight intensifiers (zenzen, mattaku, tootei, ikkoo-ni, chittomo, sukoshi-mo, kesshite, totemo) by semantic features of scalability (absolute or relative), nature of modified object (abstract/concrete) and grounds for modification (evidential or epistemic). Then we compare the meaning of utterances with the adverbs used in similar contexts. And this leads us to conclude that the pragmatics of a negative-polar adverb in Japanese is closely related to the cognitive mechanisms imprinted in their semantic structure. For instance, the etymology of “down to the very bottom” as the metaphor root in the base of “complete screening of evidential data” in tootei appears related to its scope of use in argumentative, reasoning contexts. “Decisive” as the key element in kesshite, assigns this negator to comissive contexts or statements where the speaker is in full control of actions or events he refers to. Ikkoo-ni as linked to an interval of time with zero occurrence of a certain event is best suited for narratives. While mattaku, referring to a complete discordance between two representations of reality, is tailored for critical utterances.