For this lecture, our department was pleased to invite Professor Toshiyuki Sadanobu from Kyoto University once again. Focusing on the theme of "Disfluency in Japanese Speech," the session explored what makes daily conversation sound natural. Professor Sadanobu kicked off the lecture with an interactive survey, asking the audience to evaluate the naturalness of various voice recordings. He then thoroughly explained the critical nuances that made certain phrases sound authentic or awkward to native ears. The lecture revealed that casual everyday conversations do not always need to flow perfectly like a news broadcast. In fact, appropriately incorporating fillers such as "eeto" (uh) or "un" (hmm) can make speech sound significantly more natural and native.