Using avatars to explore communication accommodation through online interactions has become increasingly popular. In this study, an avatar was adopted as a medium and employed by an experimenter who communicated with participants through the avatar using real-time voice conversion, which differs from studies utilizing chatbots with text-to-speech functions. Through the avatar, the experimenter engaged participants in a word-guessing game, during which the avatar’s facial expressions and pitch were manipulated. The results indicate that changes in the avatar’s pitch significantly influenced participants’ pitch height and range, demonstrating accommodation to the avatar’s pitch. However, this accommodation was observed to be non-mutual. In contrast, neither changes in the avatar’s facial expressions nor the interaction between pitch and facial expressions had a significant effect on participants’ pitch. Overall, the successful replication of pitch accommodation observed in face-to-face interactions highlights the feasibility of using avatars to investigate communication accommodation.