Prince Yamashiro no oe (山背大兄王)
Prince Yamashiro no oe (year of birth unknown - December 30, 643) was a member of the Imperial family in the early seventh century according to "Nihonshoki" (Chronicles of Japan). There is no description in "Nihonshoki" that he was a son of Prince Umayado (Prince Shotoku).
According to "Nihonshoki", a successor issue appeared after the death of Emperor Suiko and SAKAIBE no Marise; SAKAIBE no Omimarise, a branch of the Soga clan, supported Prince Yamashiro no oe. As a result, Prince Yamashiro no oe competed against Emperor Jomei backed by SOGA no Emishi for the Imperial Throne. However, since Emishi called for prudence by Prince Yamashiro no oe, Prince Tamura (Emperor Jomei) inherited the throne.
There are a couple of theories as to why SOGA no Emishi blocked Prince Yamashiro no oe in his bid for the Imperial Throne; one is that Prince Yamashiro no oe was still young and immature and hated Prince Yashiro no oe's popularity and the other one was that he had to avoid further confrontation with anti- Soga clan forces by allowing the ascent of Prince Yamashiro no oe since the imperial family and the subsequent emperor Suiko were supported by the Soga clan.
However, when the power in the Soga clan transferred to SOGA no Iruka, son of Emishi, Iruka planned to enthrone Furuhito no Oe no Miko, who Iruka could control at his will, and Iruka put up Empress Kogyoku as a interim successor. As a result the relationship between Prince Yamashiro no oe and the Soga clan crucially deteriorated.
On November 1, 643, SOGA no Iruka sent KOSE no Tokuta, HAJI no Ite Muraji and OTOMO no Nagatoko to attack Prince Yamashiro no oe at Ikaruganomiya Palace. Prince Yamashiro no oe's fellow Mitsunari (三成) and more that a dozen toneri (palace servant) fought back, killed HAJI no Ite Muraji with an arrow and left horse bones to make Iruka believe Prince had died. Prince Yamashiro no oe escaped with MIWA no Fumiya no Kimi (grandson of MIWA no Kimisakau who served for Emperor Bitatsu), TONERITAME no Muraji and his daughter UDA no Moroshi, ISE no Abeno Katabu and other followers ran to Mt. Ikoma. Vassal MIWA no Fumiya no Kimi advised the prince "乘馬詣東國 以乳部爲本 興師還戰 其勝必矣 (Escape to the East and prepare to fight back against Iruka), but the prince didn't want to fight and said "如卿所 其勝必然 但吾情冀 十年不役百姓 以一身之故 豈煩勞萬民 又於後世 不欲民言由吾之故 喪己父母 豈其戰勝之後 方言丈夫哉 夫損身固國 不亦丈夫者歟" (if we take up arms and fight against Iruka, surely we will win. However, I don't want to cause the peasant great hardship due to my problem. I'll give myself to Iruka. SOGA no Iruka got information discovering Prince Yamashiro no oe in the mountain and issued an order to TAKAMUKU no Kunioshi to arrest him, but he refused.
At last, Prince Yamashiro no oe and his followers came down from the mountain and entered into Hokyu-ji temple, and the prince, his wives and concubines and all other family members hanged themselves, as a result, the imperial Joyu family ended. SOGA no Iruka was furiously angry when he discovered that Iruka was responsible for the death of Prince Yamashiro no oe. Although the location of Prince Yashiro no oe's graveyard is unknown, there is a tradition saying that a hill called Oka no hara near Horin-ji Temple (Ikaruga-cho) is his graveyard.
At this time, the Imperial Throne wasn't directly hereditary so a person who was appropriate in the Imperial family was selected. Its criteria was personality, age and blood relationship with previous Emperors and lords. This is because the Imperial family didn't have absolute power since their responsibility was to manage local ruling families. Furthermore, it is said that Emperor Bidatsu and Emperor Yomei competed over succession race after Empress Suiko.
Also it is assumed that many imperial families were involved in the attempted assassination of Prince Yamashiro. Further incidents could have occurred because of the tensions between SOGA no Iruka who disfavored Prince Yamashiro no oe and the imperial families who wanted to have an advantage in the succession to the throne.
The system of successor selection at that time led to the demise of the Jogu imperial family.
Jogu Shotoku Hooteisetsu (Biography of Shotoku Taishi)
According to the "Jogu Shotoku Hooteisetsu" (Biography of Shotoku Taishi), Yamashiro no oe no o was a son of Umayato no toyotomimi shoutoku hoo, holly king, (此王有賢尊之心棄身命而愛人民也、後人与父聖王相濫非也) and his mother was daughter of SOGA no Umako, TOJIKO no Iratsume, his wife was Tsukishime no kimi, and his children were NANIHAMAROKO no miko, MAROKO no miko, YUGE no miko, SASA no himemiko, MISHIMA no himemiko, KAFUKA no miko and OHARI no miko.
December 3, 643, a son of SOGA no Toyura no emishi no omi, Iruka no omi □□ Hayashi no Tairo killed YAMASHIRO no oe and 15 of his followers and family members in Ikarugano-miya palace.
(□is missing word)
Shotoku Taishi Den Hoketsuki (聖徳太子伝補闕記)
According to "Shotoku Taishi Den Hoketsuki," Okoma no hoshi (Buddhist priest) (also called Koma no Daihoshi who were selected as one of ten supreme Buddhist leaders in 'Edict of monks and nuns in the Taika era' issued by Emperor Kotoku on September 6, 945 after Taika no Kaishin [Great Reformation of the Taika Era]) killed YAMASHIRO no Oe no o's son, YUGE no miko who was in Ikaruga-dera Temple six days later after the incident.