P Nishitonotsuka-kofun Tumulus (a large keyhole-shaped tomb mound in Nakayama Town, Tenri City, Nara (西殿塚古墳)
Nishitonotsuka-kofun Tumulus (also known as Nishitonozuka-kofun Tumulus) is a large keyhole-shaped tomb mound in early Kofun period (Tumulus period) in Nakayama Town, Tenri City, Nara Prefecture.
It's the largest tumulus among the Oyamato-kofun Tumulus Cluster which spreads over the south of Tenri City, and it's situated at the site of Tashiraka no Himemiko Fusumada-ryo Mausoleum which was written to be in Yamabe County by Engishiki (an ancient book for codes and procedures on national rites and prayers). And it was identified as the present Tashiraka no Himemiko Fusumada-ryo Mausoleum by the Imperial Household Agency. But since there were Kibi-style ceremonial vessel stands, same as Hashihaka-kofun Tumulus, were lined in the back circular part (by Terasawa, 2000), and also because of the shapes of Haniwa (unglazed terra-cotta cylinders and hollow sculptures arranged on and around the mounded tombs) and the mound, there is another idea that it was a tumulus for okimi (great king) in the period after Hashihaka-kofun Tumulus (by Shiraishi, 1999). Therefore, the age of its construction is estimated from the late third century to the early fourth century (by Shiraishi, 1999; Terasawa, 2000; Wada, 2003). But in this way, the age of its construction doesn't match the year of birth and death of Tashiraka no Himemiko (Princess Tashiraka). If such case, Fusumada-ryo Mausoleum is considered to be the only tumulus around the area, Nishiyamazuka-kofun Tumulus, which was believed to be constructed in the sixth century in Yamabe County stated in Engishiki (by Wada, 2003).
There's also an approach to suppose the deceased person under the assumption that it was a grave of okimi after Hashihaka-kofun Tumulus. First, by presuming that the deceased person in Hashihaka-kofun Tumulus was Himiko (first known ruler of Japan), the deceased person in Nishitonotsuka-kofun Tumulus could be the next king such as Toyo (a relative and a successor of Himiko) (by Shiraishi, 1999). Also, from a record saying that the grave keeper of the burial mound of Emperor Suijin kept Fusumada-ryo Mausoleum as well, there is an interpretation that Nishitonotsuka-kofun Tumulus was the burial mound of Emperor Suijin (Wada, 2003).
It is under the control of the Imperial Household Agency, and is closed to researchers and nationals.
Shape of the mound
It was transversely constructed on the slope of Mt. Ryuo. The principal axis roughly lies north and south, as the front square part faces to the south and the back circular part to the north.
The total length of the mound is 234 meters, the back circular part is 135 meters in diameter, and the front square part is 118 meters wide. It has a three-tiered structure, and is covered with fukiishi (a stone covering an old tomb). The back circular part is circle-shaped, and the side of the front square part gently forms an arc and opens at the edge, and it slightly shapes like a plectrum at its front. Tiered structure is recognized but the tiered structure at the front square part disappears at the narrowest part and it doesn't link to the back circular part. Surrounding moat was made by digging the ground a little deeper. Fukiishi and cylindrical haniwa were identified.
It's morphologically characterized by having a square platform (square 35 meters on a side and 2.6 meters high) at the top of the back circular part, and there is also the same shape (22 meters on a side and 2.2 meters high) but a little smaller platform was made at the front square part. This leads the idea that there were burial facilities for different persons under the square platforms at the back circular part and at the front square part respectively (by Shiraishi, 1999). Square platform is a huge platform for ritual which was made over the buried dead. It had not yet been made in Hashihaka-kofun Tumulus, so this was an earliest setup of a platform.
In 1988, from the report by the Imperial Household Agency, ceremonial vessel stands and ceremonial jars were revealed. In 1993, many large vessel-stand shaped haniwa whose rims are 50 to 70 centimeters in diameter and has dark spots and tiered rims, and the oldest Totsuki-style cylindrical haniwa were found. Saw-tooth pattern of the lines were engraved on the outside of the rims, and the outer surfaces were laterally and longitudinally scratched, and its inner surfaces were pulled into shape by stroking. There were also jar shaped haniwa. It seems possible that they were used at the top of the mound.