This paper investigates the Japanese writer Minamoto Sitagau's intuitions on Chinese tones reflected in his work ”Fong-tong Yuan-cheng Cai-zih He-yuan-yuan Fu 奉同源澄才子河原院賦”. The paper starts by making an analysis on the prosodic schemes utilized in ”He-yuan-yuan Fu 河原院賦”, and identifies its characteristics in syllable number, structuring, rhyming practice, and terminal tonal modulations. A comparison is then made between these and those recorded in the two literary guidebooks ”Zuo-wun-da-ti 作文大體” and ”Fu-pu賦譜” in order to trace the possible origins Minamoito's prosodic schemes. Exploring next the arrangements of level vs. oblique tonal modulations in ”He-yuan-yuan Fu”, this paper points out that Minamoto did pay attention to matching and manipulating the level-oblique tonal oppositions across doublets and within the same sentences. However, some disharmonious arrangements of level-oblique tones have been observed, which are found mainly toward the latter half of this poetic work. Evidence provided by two relevant contemporary historical documents ”Sheng-shih-shih-lun 省試詩論” and ”Dou-shih-sing-shih 鬪詩行事” showed that Minamoto was generally knowledgeable about poetic use of Chinese tones, but he apparently faltered at the performance level when he dealt with more complicated verses like ”He-yuan-yuan Fu”.