While English exhibits a clausal-manner alternation that is sensitive to where adverbs occur in clausal structure (e.g., Rudely, John left vs. John left rudely), it has not been clear to what extent Japanese behaves the same way. The present study argues, in the spirit of a scope-based theory of adverb licensing, that there is evidence that the Japanese adverbial system is scope-based similarly to its English counterpart. Focusing on mental attitude adverbs, the paper argues that Ernst’s (2002) generalization holds for Japanese: that subject-oriented adverbs lose their otherwise available clausal readings when pure manner adverbs c-command them in the same clause. The paper also claims that clausal mental attitude adverbs must be clause-mates of Tense, which is not reduced to the scope-based theory.