After the fall of Baekje Kingdom, the refugees moved to Japan. This study investigates the traces of refugees from the Korean Peninsula including Baekje, across the entire eastern part of ancient Japan (東國) including Kantō and Tōhoku. Next, the Baekje Wang-clan and Baekje-based clans who had settled in the Kantō region in the 8th-century Nara (奈良) period and the Heian (平安) period since the 9th century were examined. The presence of Baekje Wang-clan and Baekje-based clans in the Tohōku region beyond the Kantō region was also described. Finally, future directions for research on the Baekje-based clans were presented.