There are various ideas related to characters in modern Japan (dramatis personae, Ito's (2005) Kyara and its self-professed successors' ideas, and situation-based self). This paper will introduce these ideas, address my definition of character (situation-based self) in detail, and discuss its significance for communication and linguistic research. The major characteristics of this definition are: (i) it is based on the traditionally taboo idea that "humans can change in response to the situation," and (ii) it is not something created by a researcher (the author), but was rather formed by speakers of Japanese in the course of daily life. I merely employed this word as it is, as a technical term. Japanese speakers are keenly conscious of the ...