Maruyama Kofun (Kaizuka)
is a Kofun period keyhole-shaped burial mound, located in the Jizodō neighborhood of the city of Kaizuka, Osaka in the Kansai region of Japan. The tumulus was designated a National Historic Site of Japan in 1956. It is also called the Overview The Maruyama Kofun is a , which is shaped like a keyhole, having one square end and one circular end, when viewed from above. It is located on a fluvial terrace of the Kogi River, and is orientated to the west. The tumulus has a total length of 73 meters with a 43-meter diameter posterior circular portion. The tumulus was originally covered in fukiishi and had a large number and variety of haniwa, including cylindrical, "morning glory-shaped", figurative and house-shaped styles. There was no trace of a moat around the tumulus, and the location and structure of the burial chamber was not clear. It is believed to have been built around the latter half of the 4th century. Six more smaller kofun (four ( and two () have been found on the grounds of the nearby Kaizuka Minami Elementary School, forming a cluster of tumuli, suggesting that this was the burial ground for local tribal chieftains during the