Kogo is asteroid #5684 and also known as 1990 UB₂. Kogo’s orbit is characterized by a semi-major axis of 2.22 Astronomical Units, an eccentricity of 0.22, a period of revolution of 1 209 days, and an inclination of 5.6 degrees. Kogo was discovered by Urata Takeshi (浦田 武) at the Oohira Station of the Nihondaira Observatory.

Kogo is named after Kogō (小督), what wasn’t her real name. Because her real name isn’t known. Her death year is unknown, too. What is known is that she was born in 1157 A.D. as the daughter of Fujiwara no Shigenori (藤原 成範), a court noble and poet and the third son of Fujiwara no Michinori (藤原 通憲), who was the chancellor and advisor of the 78th Emperor of Japan. A theory identifies Kogō (小督) with Seiko (成子), a known girl of the Fujiwara (藤原) Clan. Kogō (小督) was the mistress of Fujiwara no Takafusa (藤原 隆房), a governor and military commander, when Takakura-tennō (高倉天皇), the 80th emperor of Japan, met Kogō (小督) and fell in love with her. According to the Heike-monogatari (平家物語), Takakura-tennō (高倉天皇) was very sad because his favorite waiting-maid deceased. So his wife, Taira no Tokuko (平 徳子), tried to spirit him up and so introduced him to the daughter of Fujiwara no Shigenori (藤原 成範) because she excelled in playing the sō-no-koto (箏), a typical Japanese musical instrument. The name Kogō (小督) means a little cheer. When Takakura-tennō (高倉天皇), after whom the asteroid Takakura is named, saw her, he fell in love with her because of her beautiful face. Takakura-tennō (高倉天皇) made her his favorite consort and nobody would have dared to contradict the emperor. She gave birth to a daughter in 1177 A.D. This was the second daughter of Takakura-tennō (高倉天皇). His first daughter was born by an even less well known member of the Fujiwara (藤原) Clan. Taira no Kiyomori (平 清盛), Japan’s grey eminence and the father of Taira no Tokuko (平 徳子), was furious because this did endanger his plan to become the true ruler in behalf of his grandson, who would have to be born by Taira no Tokuko (平 徳子) and as the first son of Takakura-tennō (高倉天皇) in order to become the emperor of Japan. Different from the standards in Europe, all children of a Japanese emperor were legitimate children. So Taira no Kiyomori (平 清盛) didn’t risk that Kogō (小督) would give birth to a son next, but ostracized her and got her kicked out of the palace. In consequence Taira no Tokuko (平 徳子), after whom the asteroid Kenreimonin is named, really gave birth to the first son of Takakura-tennō (高倉天皇). Then Taira no Kiyomori (平 清盛) forced Takakura-tennō (高倉天皇) to abdicate and put his own grandson on the Chrysanthemum Throne. There is a record that Fujiwara no Sadaie (藤原 定家), a seemingly rather distant relative, made a visit at the sickbed of Kogō (小督) in 1205 A.D. This is the last of what is recorded on Kogō (小督).

The asteroid Kogo indicates talent in playing string instruments, especially if these are Japanese. Kogo also indicates that a love affair is in the way of a political ruse. Kogo also indicates the special kind of relationship, when a wife introduces her rival herself to her husband and also when this rival gets in a strife with the wife’s father.