Cross-linguistic research on nominalized vs. non-nominalized clausal complementation has shown that nominalized clauses tend to be associated with factive interpretation more readily than non-nominalized clauses are (Özyıldız 2017; Lee 2019; Bondarenko 2020; Bochnak and Hanink 2022). In the study of Japanese, for instance, koto, which can turn a finite clause into a nominal element, has been often described as the factive complementizer, as opposed to another element to, which has been described as a non-factive complementizer (eg, Kuno 1973). 1 In this paper, we present a case study on nominalized clausal complements in non-factive belief reports, involving-ta-nun-kes and (-to-yuu)-no at the right periphery of such complements in Korean (1)(Shim and Ihsane 2015) and in Japanese (2), respectively.(1) na-nun [kay-ka swukecey-lul ta ha-yass-ta-nu