Adjectives of sensation and emotion (Experiencer adjectives) in Japanese can take only the speaker as their experiencer subject in declarative root sentences and the addressee in interrogative root sentences in conversation. This constraint, which I call the Experiencer restriction, is lifted in other various clauses, however. This dissertation examines the Experiencer restriction across clausal types under scrutiny, and presents two analyses of the phenomenon, following the claim by Krifka (2001, 2004), Speas and Tenny (2003) and others that speech acts are syntactically realized. First, I introduce the phenomenon and give a brief review of its analyses which were made before the proposal of the speech act projection (Chapter 1). Then I explain the Japanese complementizer system and provide basic data on the Experiencer restriction across clausal types (Chapter 2). A conceptual-structural analysis of Experiencers by Jackendoff (1990) and syntactic analyses of Experiencers by Landau (2010) and others suggest that Experiencers are mental locations. Based on that, I propose a situation semantic analysis of Experiencers as mental locations in Chapter 3. In Chapter 4, I apply the situation-based analysis to the Experiencer restriction in non-restrictive relative clauses after arguing that Schlenker’s (2010, 2013a,b) uni-dimensional analysis explains properties of Japanese non-restrictive relative clauses. In Chapter 5, I turn to another possible analysis, according to which Experiencer NPs agree with an epistemic modal head via a sentient feature [sen] and an index feature [n]. It can be seen as a revision of Tenny’s (2006) feature checking analysis, which claims that a [+sentient] feature and a [+discourse participant] feature are checked. I argue that the principle of parsimony favors the situation-based analysis over the feature-checking one. In Chapter 6, I compare recent formal analyses of the Experiencer restriction with my analyses. This dissertation improves our understanding of situation semantics in connection to mind-body dualism. Also, it shows that study of Experiencers in Japanese gives us an insight into the syntax/semantics/pragmatics interface. It tells us not only properties of Experiencers but also properties of speech acts and the speech act projection.