古代日本の異族婚と神話の構造Inter-Tribal Marriage and Mythology of Ancient Japan
This time, we will explore the mythological structures hidden within ancient layers, focusing on a very intriguing goddess, Toyotamahime (豊玉比売). According to Japanese mythology, Toyotamahime appears as a goddess who married into the lineage of the amatsukami (天つ神), the gods of heaven, and gave birth to Ugayafukiaezu (鵜葺草葺不合命), who was the father of Japan’s first emperor, Emperor Jinmu. In other words, she was Emperor Jinmu’s grandmother. It is said that when Toyotamahime went into labor, she declared, “I cannot give birth to a divine child of the Amatsukami in the ocean,” and voluntarily traveled north along the sea route, entered a cave on the coast, and constructed a birthing hut where she delivered Ugayafukiaezu.
The site of this legend remains today at the majestic Udo Shrine (鵜戸神宮), situated on a steep cliff in southern Kyushu. I have personally visited this shrine and felt that it preserves extremely ancient customs. Given the geographical environment of Udo Shrine, it seems plausible that Toyotamahime’s origins may trace back to the southern Ryukyu Islands region. I am currently investigating this possibility and plan to deepen my understanding over the next three years.
The kami whom Toyotamahime married was Yamasachihiko (山佐知毗古). In the divine age (神代), kami often had numerous names, and thus this deity is also called Hoori (火遠理命). Hoori’s lineage traces back to his father Ninigi (邇邇芸命), whose own father was Oshihomimi (天忍穗耳命), born from the divine pact between Amaterasu (天照大神) and Susanoo (須佐之男命). At the time of Oshihomimi, the Amatsukami had not yet descended from the Takamanohara (高天原) to the Ashihara-no-Nakatsukuni (葦原中国), known as the “Tenson Korin” (天孫降臨).
The accounts of this descent in the Kojiki and Nihon Shoki generally align, but attention must be given to differences in the portrayal of the deity who commanded Ninigi to descend. The Kojiki records that Ninigi descended from Takamanohara to rule Ashihara-no-Nakatsukuni by the command of the heavenly deity Amaterasu. In contrast, the Nihon Shoki attributes the command to Takamimusubi (高御産巣日神), a heavenly deity who greatly cherished Ninigi. This divergence suggests that the Amatsukami cannot be viewed simply as a single unified lineage but instead indicate a more complex ancestral structure from ancient layers. From a broader perspective, I personally interpret the Amatsukami as divided into two distinct lineages: the “Takamimusubi lineage” and the “Amaterasu lineage,” each originating from significantly different tribal roots.
On the other hand, Ninigi is positioned as the child of Oshihomimi, who himself was considered Amaterasu’s offspring, through his marriage to Takuhatachijihime (栲幡千千姫命), the daughter of Takamimusubi. Ninigi was thus born in Takamanohara. This indicates that within Takamanohara, an inter-tribal marriage occurred between the “Amaterasu lineage” and “Takamimusubi lineage,” exemplified by the union of Ninigi and Takuhatachijihime, clearly representing a marriage between distinct clans. Notably, this inter-tribal marriage took place on the plane of Takamanohara, with both Amaterasu and Takamimusubi positioned as Amatsukami. However, Japanese mythology assigns Takamimusubi a special position as a “Koto-Amatsukami” (別天つ神), thereby expressing the utmost reverence and placing him in a particularly elevated divine rank. The ancient layer depicted here suggests that before migrating to the Japanese archipelago (Ashihara-no-Nakatsukuni), tribal groups from the ancient continent had already formed inter-tribal genealogies.
The child symbolically positioned at the convergence of these lineages was Ninigi. In other words, Ninigi represents the integration of the two distinct clans of Amatsukami— “Amaterasu lineage and Takamimusubi lineage”—and is positioned at the forefront of the “Tenson Korin,” symbolizing the migration across the sea from the continent to the Japanese archipelago. According to the myths, Ninigi descended onto Mount Takachiho (present-day Mount Takachiho in the Kirishima Mountains), located in Hyuga (present-day Miyazaki Prefecture), in southern Kyushu. He then traveled further south toward present-day Nichinan City in Miyazaki Prefecture, where he married the beautiful Konohanasakuyahime (木花佐久夜比売). Konohanasakuyahime was the daughter of the Kunitsukami (国つ神) Ooyamatsumi (大山津見神) and Kayanohime (鹿屋野比売神), thus identifying her as a princess deeply rooted in the local landscape.
Here, the mythological structure reveals a new dimension of inter-tribal marriage on the stage of Ashihara-no-Nakatsukuni, transitioning from the unified dimension of the Amatsukami (“Amaterasu lineage - Takamimusubi lineage”) at the level of Takamanohara. At this time, Ninigi becomes suspicious of Konohanasakuyahime’s overnight pregnancy and harshly accuses her of infidelity. It is crucial to note here that at this stage, the Amatsukami were not yet ruling over Japan at all. Indeed, Konohanasakuyahime, representing the Kunitsukami, is enraged by Ninigi’s accusation, and swears an oath stating that if the children are truly Ninigi’s offspring (children of the Amatsukami), they will survive unharmed even if she sets fire to her hut, but if not, they will burn to death. She then sets the hut ablaze. The safe birth of three children here proves their divine lineage from the Amatsukami, highlighting the complex inter-tribal marriage that took place in this small location in Nichinan between the initial “Amatsukami (immigrant lineage)” and “Kunitsukami (native lineage).” More explicitly, it implies that at this moment, the Kunitsukami—still regarded primarily as localized kami—were more powerful.
Thus, three sons were born: the eldest, Hoderi (火照命); the second, Hosuseri (火須勢理命); and the third, Hoori (火遠理命). While traditional Japanese village society is commonly thought of as adhering to primogeniture, this was a much later cultural practice. Ancient layers instead indicate customs similar to those of the ancient Chinese Zhou dynasty, where the third son inherits the throne. Especially since the Amatsukami had continental origins, we can see that remnants of these ancient Chinese customs were preserved as they became involved in the Japanese archipelago.
Subsequently, Hoori marries Toyotamahime, constituting another inter-tribal marriage. A notable feature of this inter-tribal union is that Hoori, appearing as Yamasachihiko (山佐知毗古), symbolizes a mountain-dwelling tribe marrying Toyotamahime, a deity from the sea-dwelling tribe. The mythological structure here represents the marriage of “mountain tribe lineage - sea tribe lineage” through the union of “Hoori - Toyotamahime,” but again, this took place within a very small, localized area. According to my independent mythological research, the necessity of this inter-tribal marriage likely stems from an ancient tribal migration in which mountain tribes, facing a depletion of mountain-based resources (“mountain fortune”), moved toward coastal areas in search of new livelihoods. Volcanic activity frequent in southern Kyushu likely forms the ancient backdrop of this migration as a distant memory. Due to these conditions, Hoori could no longer govern his territory and fled to the coast. However, the marine territory was already governed by his elder brother, Hoderi, known as Umisachihiko (海佐知毗古). Thus, the myth develops into a conflict between brothers over territorial control.
Yet, lacking maritime knowledge, Hoori becomes uncertain about how to proceed. At this juncture, he encounters Shiotsuchi (塩椎神), an elder who knows everything about the sea. Shiotsuchi teaches him about ocean currents and navigation, enabling Hoori to acquire maritime skills and eventually cooperate with the sea tribe. Shiotsuchi is an elder from a tribal group deeply familiar with the ocean currents flowing from southern Kyushu toward Amami and Ryukyu. Following Shiotsuchi’s guidance, Hoori heads to the territory governed by the god of the sea, a remote island, where he meets and marries Toyotamahime, daughter of Watatsumi, the god of the sea.
However, after three years, once Hoori reveals his original purpose, he returns from this remote island to southern Kyushu, the place of his origin. This connects back to the earlier account in which Toyotamahime, upon feeling labor pains, declares, “I cannot give birth to a divine child of the Amatsukami in the ocean,” travels northward by sea route, enters a seaside cave, builds a birthing hut, and gives birth to Ugayafukiaezu.
During childbirth, Toyotamahime, secluded in the birthing hut (cave), instructs Hoori not to look at her while she gives birth, establishing a taboo. However, driven by curiosity, Hoori breaks this taboo, peeking inside, only to see Toyotamahime transformed into a massive Yahirowani (八尋鰐), a shark-like creature. Humiliated by her husband’s breach of the taboo, Toyotamahime declares that she will sever the sea route between sea and land as punishment for the disgrace. She wraps the newborn child in grass, leaves it on the shore, and returns to her homeland. The child left behind in southern Kyushu is Ugayafukiaezu. Consequently, Hoori’s tribe loses contact with the sea tribes entirely.
This myth vividly recalls the existence of taboos that strictly forbade couples—even spouses—from witnessing the customs of the other tribe, particularly in sensitive events such as childbirth, death, and sacred rituals. Tales of husbands violating such taboos in inter-tribal unions notably appear not only in the cases of Ninigi and Konohanasakuyahime, or Hoori and Toyotamahime mentioned previously but also further back in the myth of Izanagi and Izanami in the “Yomi-no-Kuni (黄泉の国)” narrative.
This context reveals the possibility that the Amatsukami strongly maintained a continental viewpoint, perceiving the places of other tribes as a form of “Takai” (他界, Other World), while positioning their own territory as the “Gensekai” (現世界, Present World). However, caution must be taken here; this simplistic binary division between Gensekai and Takai is essentially a modern construction. When considering ancient Japan, it is critical to retain a more pluralistic viewpoint, in which the Gensekai and Takai intermingle and coexist. Additionally, even the concept of “Takai” in mythology is pluralistic, manifesting in diverse forms such as “Yomi (黄泉国),” “Nenokatasu (根之堅州国),” and “Tokoyo (常世国).”
Examining these myths from the perspective of inter-tribal marriage, we find that although the Japanese term “異族” (izoku, different tribes) literally suggests “distinct tribes,” it is more accurately conceptualized through the homophonic “異俗” (izoku, different customs). Due to the multifaceted nature of the Japanese language, even identical pronunciations hold diverse meanings, and indeed, this latter interpretation—異俗, referring to distinct customs and lifestyles—better represents the nature of early inter-tribal marriages. Later on, groups descending from the Amatsukami, who were proponents of “rice paddy agricultural culture” (水田稲作民的農耕文化), expanded their unified governance aspirations. They spread rice paddy agriculture across the Japanese archipelago, symbolically associating rice with the Amatsukami and ultimately with the emperor (“Rice = Amatsukami = Emperor”). Yet even today, rice agriculture does not uniformly blanket all of Japan, leaving many regions as “blank areas.” Moreover, the very concept of “blank areas” itself presupposes an archaic rice-centric worldview. Consequently, it is essential to recognize that even now, a single, unified system centered on rice, even where it holds the majority, does not cover everything. Seriously examining these often-overlooked blank spaces provides a crucial route toward comprehending Japan’s authentic identity.
As illustrated by the myths of ancient inter-tribal marriages introduced here, these narratives clearly depict events occurring at highly localized scales, demonstrating the immense struggles involved even in simple unions between mountain and sea tribes. In later periods, these tensions explicitly emerge as contact between the Jomon and Yayoi tribes. After this period of localized blending (during the Yayoi period), yet another complex dimension emerges as Jomon/Yayoi tribes intersect with Kofun tribes. In the Kofun period, the system that enshrined “rice paddy agriculture” was itself a different custom (isoku, 異俗), and under a rule centered on rice, the earlier slash-and-burn cultivation of tubers, root crops, and grains, from Jomon times and from the Yayoi, came to be regarded as inferior. A movement began to absorb and to exclude those ways of life, marking a critical turning point vividly captured in the transition from the “Age of Kami” (神代巻) to the “Age of Humans” (人代巻) as depicted in the Kojiki and Nihon Shoki. Within this transitional phase exists an intermediary dimension of “Imperial descendants” (皇孫), and beneath this layer are vibrant pluralistic regions inhabited by peoples described as “matsurowanu” (まつろわぬ民).
While understanding this nuanced historical background might be challenging, I hope that this exploration aids readers in better grasping the intricate nature of Japanese mythology. I plan to continue sharing my insights to further illuminate this topic.