The conjunctive particle “shi” in Japanese at the end of a sentence has a wide range of meanings, ranging from cases where it retains its original meaning and function, to cases where it acquires a new meaning and functions as a final particle. This paper studies how such changes in “shi” are brought about. First, based on prior research, we assume that there’s a “main situation” as a premise of utterances ending in “...shi”, and that “...shi” represents a “supporting situation” for the main one. It is stated that the transformation of “shi” into an ending particle correlates with the “backgrounding of the main situation”, the “abstraction of the main situation”, and the “unification of the supporting situation”. As “shi” transforms into an ending particle, there are more cases where an utterance can work without “shi,” However, the presence of “shi” allows the speaker to express a defiant attitude.