Japanese does not have number morphology or agreement. Thus, a bare noun like inu ‘dog’ can refer to a single dog or more than one dog, depending on contexts. This fact has raised much controversy about whether grammatical number exists in Japanese and has led some researchers to regard Japanese as a language lacking number specification in bare nouns (Chierchia 1998; Martin 1975; Nakanishi & Tomioka 2004; Nomoto 2013) and abstract number/phi agreement (Fukui 1986, 1995, Kuroda 1988; Fukui and Sakai 2003, Saito 2007, 2017, among others). Recently, however, Watanabe (2017) has provided strong evidence against such views, based on partitive interpretations of bare nouns. In this paper, I uncover yet another novel piece of evidence for grammatical number specification in Japanese from indeterminates. Surprisingly, they are obligatorily specified for singular despite the lack of number morphology or classifier.