The Konnō Hachiman-Gū home page tells us that the shrine was was founded on January 15, 1092 during the reign of the 73rd emperor, Horikawa, by Minamoto Yoshiie. This followed his victory in the Gosannen War (後三年合戦, lit. "Later Three-Year War"). One of his allies in the campaign was Taira-no-Taketsuna, 平武綱, a descendant of the 50th emperor, Kanmu. Taketsuna had dedicated two war flags symbolizing the sun and the moon at Mount Myōken in Chichibu in Saitama-ken (possibly the present Mt. Bukō) , and Yoshiie was convinced that it was Taketsuna's belief in the two flags which enabled his victory. Accordingly he had the moon flag enshrined at what is now the site of the Konnō Hachiman-Gū. In due course Taketsuna's son, Shigeie, 重家, inherited the clan leadership and for military service rendered to the emperor in Kyōto was awarded the name of Shibuya. With the clan settling around the shrine and building a castle the area became known as Shibuya, and it may be to this that the modern Shibuya-ku
From Merged Shrines
Mitake Jinja 御嶽神社
Tamatsukuri Inari Jinja 玉造稲荷神社
Konnōmaru Jinja 金王丸社
Earliest mention of: 1092
Annual Festival: Sept. 15
owes its name. Shigeie and his wife were childless and began praying for a child at Hachiman-Gū. One night Shigeie had a vision in which he saw Vajrayakṣa, one of the five kings of knowledge in Esoteric Buddhism, present in his wife's womb. Following this auspicious omen a son was born and given the name Konnō, which consists of the first and last characters, 金 and 王. of Vajrayakṣa's name in kanji, 金剛夜叉明王（Kon-gōyasha-myo-ō). At the age of 17, Konnō joined Minamoto Yoshitomo's army and distinguished himself in the latter's victorious Hogen Rebellion (保元の乱) campaign of 1156. Three years later, though, Yoshitomo attempted to seize national power for himself in the Heiji Rebellion but was defeated, and although managing to escape with his life was later treacherously murdered in his bath. Konnō stood by Yoshitomo's side during all of this, and after his commander's death took monkly vows and travelled around Japan praying for the repose of Yoshitomo's soul.
Five minutes from the East exit of Shibuya Station. The visually most interesting aspect of this shrine is probably the prayer hall. It was built in 1612 during the reign of the second Tokugawa shōgun, Hidetada, as a direct result of speculation about who would be the third shōgun, Hidetada's elder son, later known as Iemitsu, or his younger son, Tadanaga. Iemitsu's wet nurse was Lady Kasuga, one of the most interesting women of her time, and, together with Iemitsu's guardian, a relatively less well-known samurai by the name of Aoyama Tadayoshi (青山 忠俊), she began working to ensure Iemitsu's succession. While Aoyama prayed at the Hachiman-Gū for the desired result Lady Kasuga contributed 80 ryo ($86,000 at current exchange ates) to strengthen the prayers' efficacy. They were successful and Iemitsu became the third shōgun. Later, when Iemitsu was undergoing his armour-fitting ceremony, Lady Kasuga contributed 100 ryo ($107,000) and Aoyama a large amount of timber for the construction of the prayer hall , which still stands today. As can be seen in the photos below, it is quite colourful and features engravings of tigers and baku, a supernatural being which devours dreams and nightmares. The two koma-inu in front of the main hall were carved in 1900.
The Shrine "Red" gate was constructed sometime between 1769 and 1801 with the help of a 150 ryo donation from a descendant of Aoyama Tadayoshi.