It is said that Muneyasu HARA (Shima no kami (Governor of Shima Province) Hara), the father of the eighteenth chief priest Nichijun brought the heads of his father Taneshige HARA and his older brother Kiyoyasu HARA (Magohachiro HARA) who were killed in the Honnoji Incident and the head of Nobunaga ordered by Sansa HONINBO to the Honmon-ji Temple and planted a holy tree and buried them in Kubi-zuka.
第18世住職、日順上人の父、原宗安（原志摩守）が本能寺の変の際、戦死した自分の父原胤重と兄原清安（原孫八郎）の首と本因坊算砂の指示で信長の首を本門寺まで持ち帰り柊を植え首塚に葬ったという。