Isotakeru is a Shinto god appearing in Japanese mythology. His name is also pronounced as Itakeru. This god appears in the "Nihonshoki" (Chronicles of Japan) and the "Sendai Kujihongi" (Ancient Japanese History), and he is thought to be the same god as Oyabiko, who appears in the "Kojiki" (the Records of Ancient Matters). He is a child of Susanoo (a god of sea and storms), and his younger sisters are the goddesses Oyatsuhime and Tsumatsuhime.
According to the descriptions in the "Nihonshoki" and the "Sendai Kujihongi," Isotakeru is worshipped as a god of forestry. Kii Province had been an important region for forestry since ancient times and it is believed that Isotakeru was worshipped by people in that industry. From the fact that the description says he is enshrined in Kii Province (formerly called 'Ki no Kuni,' which literally means 'country of trees') and also from an annotation in the "Sendai Kujihongi" which says 'he is also called Oyahiko', Isotakeru is regarded as the same god as Oyabiko of Ki no Kuni, who gave refuge to Okuninushi (the chief god of Izumo in southern Honshu) in the "Kojiki." He is thought by some to be Oyabiko no kami (the one identified with the god of disorder, Magatsuhi no Kami) who was the children of Izanagi and Izanami (the god and goddess who created the Japanese islands), but he is in fact a different deity.
In the first volume of the "Nihonshoki," the fourth issho (addendum) of the the eighth section, which describes the defeat of Yamatanoorochi (the Eight-Forked Serpent), says as follows. The issho says as follows. Susanoo behaved wickedly. Accordingly the gods punished him by confiscating his property and banished him. Susanoo then descended to the country called Silla (on the Korean Peninsula) with his child named Isotakeru no Kami, and went to a place called Soshimori.
In that place he complained, saying 'I do not want to stay here.'
Thus he made a boat from clay and used it to travel to the east, and then he reached Mt. Torikami located at the upper reaches of Hi-kawa River in Izumo Province. In that place, there was a man-eating monster serpent. Susanoo defeated the serpent with a sword called Amanoha-hakiri no Tsurugi. The sword chipped as he cut the serpent's tail. He cut up the tail to see inside it, and found a mysterious sword there.
Susanoo said, 'This cannot pass into my possession.'
Therefore he sent Amanohukine no Kami, who was a fifth-generation descendant of Susanoo, to offer it to heaven. This sword is what is now called Kusanagi no Tsurugi. When Itakeru no Kami first descended from heaven, he brought a large number of tree seeds. However, he did not sow them in Korea, and brought all of them back to Japan. He sowed the seeds all over the country of Oyashima (Great Myriad Islands, which is another name for Japan) starting with Tsukushi (Kyushu), until finally the whole country was covered with green mountains. Thus Itakeru no Mikoto is called Isaoshi no Kami (the 'deserving god') because of this story. He is the great god who is enshrined in Kii Province. In summary, Isotakeru descended to Soshimori in Silla with Susanoo, who was banished from heaven (which is called Takaamahara in the "Kojiki"), and then they together moved to the place called Torikaminotake located at the upper reaches of Hii-kawa River in Izumo Province by a hani-bune (clay boat) because Susanoo said he did not want to stay in Soshimori. Isotakeru brought many tree seeds when descending from heaven but did not sow them in Silla, instead taking all of them to Japan, where, starting in Kyushu, he sowed them throughout Yashima (Japan). It is said this is why Japan became a country covered with green mountains.
The fifth issho in the same section says as follows. The issho says as follows.
Susanoo said 'There is gold and silver on the islands of Korea. It would not be good if there were no ships in the country where my child rules.'
He pulled out his mustache and beard and threw them, and they became Japanese cedar trees. He pulled out his chest hairs and threw them, and they became Japanese cypress trees. The hairs of his buttocks became podocarpus trees. His eyebrows became camphor trees.
He designated the purpose of each tree, saying, 'Cedar and camphor trees, these two types of trees are good for making ships. Japanese cypress trees are good for building shrines. Podocarpus trees are suitable for making coffins for people in this world. Let us sow a good many tree seeds.'
Susanoo's child is called Isotakeru no Mikoto.
His younger sister is Oyatsuhime no Mikoto
The next sister is Tsumatsuhime no Mikoto. These three gods worked hard to sow the seeds. They are enshrined in Kii Province. Then Susanoo went to Mount Kumanarinotake and he finally entered Nenokuni (the underworld). The term "棄戸" is pronounced "sutahe" (coffin), and the term "柀" is pronounced "maki" (podocarpus). In summary, this issho says Susanoo created various trees such as Japanese cedars from his mustache and beard, Japanese cypresses from his chest hairs, podocarpus from the hairs of his buttocks, using his body hair including his eyebrows to make each kind of tree, and Isotakeru and his two younger sisters (Oyatsuhime and Tsumatsuhime) planted those trees throughout Japan.
Both the issho versions say he is now enshrined in Kii Province.
According to the folklore of Izumo, Susanoo and his children landed on coast of Isotake, in Iwami Province, which was near to Izumo Province, and then they left for Izumo Province.
The following description is seen in the Chigihongi (the True Record of the Earthly Deities) in the fourth volume of the "Sendai Kujihongi," which was submitted during a nihongi-koen (Heian period studies and lectures on the Nihonshoki) although it's authenticity is disputed.
Susanoo descended from heaven to the place called Soshimori, in Silla, with his child named Isotakeru no Kami. Soshimori is the name of a place in Silla. Soshimari, seen in the section on Goryeo music in the Wamyosho (a famous Heian-period Japanese dictionary) is a song that tells of the customs of that place.
After that, he said aloud, 'I do not want to stay here.'
So he made a clay boat and traveled in it to the east. He reached the place called Torikami, which is in the upper reaches of the Hi-kawa River in Izumo Province and the upper reaches of the Kaai-kawa River in Aki Province.
(Story of Yamatanoorochi's defeat omitted)
Susanoo entered Nenokuni from Mount Kumanasunomine. His child, called Isotakeru no Kami, brought seeds of various types of trees and crops when he descended from heaven, but he brought them back to Japan without sowing them in Korea. He eventually started to sow the seeds in Tsukushi and then spread them all over the country of Oyashima, filling the country with green mountains. Isotakeru no Mikoto achieved great things. He is a great god who is enshrined in Kii Province. According to another story, Susanoo had three child gods, the child named Isotakeru no Mikoto, his younger sister, named Oyahime no Mikoto, and the youngest sister, named Tsumatsuhime no Mikoto. Also, they worked hard sowing many seeds and moved to Kii Province. In other words, they are the gods who are enshrined in this province.
This mikoto (god) swears with Amaterasu Omikami (the Sun Goddess)...and the god named Isotakeru no Kami, also known as Oyahiko no Kami, followed by Oyahime no Kami and Tsumatsuhime no Kami. These three gods are in Kii Province. In other words, they are gods who are enshrined by Kiinokuni no miyatsuko (the governor in Kii Province).