After the 1923 Great Kantō earthquake and its two major aftershocks in January 1924, seven wooden pillars suddenly appeared in the paddy fields along the Koide River. Subsequent investigations found three more pillars still buried in the ground. These pillars are made of "hinoki" wood, with a diameter of 60 centimeters, and have a surviving length of 3.6 meters. From the location, it was postulated that these are the remnants of a bridge across the Sagami River as was mentioned in the medieval chronicle "Azuma Kagami". Per the "Azuma Kagami", the bridge was constructed by Inage Shigetada, a relative of Hatakeyama Shigetada, who had an estate in this area. Inage Shigetada was married to a younger sister of Hōjō Masako, and was thus Minamoto no Yoritomo's brother-in-law. Yoritomo is recorded as having attended the funeral of the wife of Inage Shigetada in 1198, crossing over this bridge. According to legend, during the return, Yoritomo's horse was spooked by the ghosts of the Taira clan and his brother Minamoto no Yoshitsune as it crossed the bridge and threw Yoritomo into the river. He fell ill and died shortly afterwards, and the ten bodyguards who accompanied him all committed "seppuku", with their graves at the nearby temple of Ryuzen-in.