Japanese sentence final particles (JSFPs henceforth) are used extremely frequently in utterances. We propose functions of Japanese Sentence Final Particles YO NE and NA that are based on a hierarchal memory model which consists of Long Term Memory, Episodic Memory and Discourse Memory. The proposed functions of JSFPs are basically monitoring functions of the mental process being done in utterance. YO shows that the propositional content of the utterance that ends with YO was already in the speaker's Episodic Memory or Long Term Memory, while NE and NA show that the speaker is processing the propositional contents with the contents of speaker's memory. The proposed functions succeed in accounting for the phenomena yet to be explained in the previous works.