三種の神器の起源と『古語拾遺』Sanshu-no-Jingi

Yesterday’s article examined the peculiar historical context of the Nanbokucho Period, an era marked by the simultaneous existence of two emperors. Emperor Go-Daigo, motivated by discontent towards the rising samurai-led government of the Kamakura Period, envisioned restoring the imperial and aristocratic authority of earlier eras. Although his revolution initially succeeded, establishing a new regime, it rapidly deteriorated into conflict with the samurai. The influential samurai leader, Takauji Ashikaga, defected, dividing Kyoto and causing the collapse of Emperor Go-Daigo’s regime within merely two years. Consequently, Emperor Go-Daigo’s faction fled Kyoto and established their own imperial court (Southern Court, 南朝) in Yoshino, Nara Prefecture, while Takauji Ashikaga established a rival court (Northern Court, 北朝) in Kyoto by enthroning Emperor Kogon followed by Emperor Komyo. Thus began an era of two competing courts and emperors.

Despite holding overwhelming military and political advantages, the Northern Court faced a troublesome issue that prevented them from decisively defeating the Southern Court: possession of the the Sanshu-no-Jingi (三種の神器, Three Imperial Regalia), which symbolized the legitimacy of imperial rule. Emperor Go-Daigo had taken these sacred regalia when fleeing Kyoto, leaving the Northern Court unable to demonstrate legitimacy. This resulted in a prolonged fifty-year division known as the Nanbokucho Period. But what exactly are these Sanshu-no-Jingi? This article will explore their origin and significance.

The origins of the Sanshu-no-Jingi trace back to Japanese mythology. According to legend, the regalia were given by the imperial ancestral goddess Amaterasu (天照大神) to her grandson Ninigi-no-Mikoto (邇邇芸命). The regalia consist of three divine items: the “Yata no Kagami” (八咫鏡, a mirror), the “Kusanagi no Tsurugi” (草薙剣, a sword), and the “Yasakani no Magatama” (八尺瓊勾玉, a curved jewel). Simply put, they are a mirror, a sword, and a jewel, revered since ancient times as the symbols of imperial legitimacy and succession. Among them, the Yata no Kagami holds particular significance, underscored by Amaterasu’s statement upon entrusting it to Ninigi, “Looking upon this mirror is the same as looking upon myself.” Owing to these mythical roots, the regalia became symbolic of the emperor’s authority inherited directly from Amaterasu, cultivating the belief since antiquity that possession of these regalia guarantees imperial legitimacy.

Interpretations of the Sanshu-no-Jingi have varied considerably throughout history, reflecting countless ideological influences linked to emperors of each era. This complicates clear understanding. For example, Shintoists during the Edo period regarded the regalia as symbols of the emperor’s virtues, integrating Confucian concepts prevalent at the time. Meanwhile, during the era of State Shinto from the Meiji period onward, the regalias were redefined as politically sacred symbols strongly affirming imperial legitimacy.

Some scholars have interpreted the regalia symbolically as a unified system representing authority over religion, military power, and ritualistic prosperity: the mirror symbolizing the sun (heaven), the sword representing military might, and the jewel representing fertility and prosperity. These varied interpretations highlight the complex historical character of the regalia, illustrating how deeply their symbolic meanings have been shaped by the contexts of their time. In a sense, the Sanshu-no-Jingi themselves reflect historical change.

Yet, a fundamental question remains: have there always been exactly three regalia since ancient times?

Although today the Sanshu-no-Jingi are accepted as proof of legitimate imperial succession, historical research suggests they may not originally have existed as a fixed set. For instance, even into the 20th century, Taoism researcher Mitsuji Fukunaga, in his examination of Taoist influences in Japan, focused on connections to Taoist symbolism from China and suggested that in ancient Japan, only the combination of the mirror and the sword was specially emphasized. According to this view, the Yata no Kagami and Kusanagi no Tsurugi were the primary imperial symbols in ancient Japan, whereas the Yasakani no Magatama might not originally have been passed down by the imperial family or directly associated with imperial succession.

In fact, Fukunaga’s perspective is not entirely original but rooted in much older historical interpretations. A notable example is found in the Kogo Shui (古語拾遺), a text written by Imibe no Hironari (斎部広成, dates unknown) in 807, shortly after the compilation of the Kojiki (712) and the Nihon Shoki (720). According to the Kogo Shui, only the Yata no Kagami and the Kusanagi no Tsurugi are described as the “Tenji” (天璽), or imperial symbols, while the Yasakani no Magatama is positioned merely as a symbol representing submission to the kami and emperor.

However, why did Imibe no Hironari publish a differing account of Japan’s ancient myths and traditions roughly a century after the compilation of the Kojiki and Nihon Shoki?

The answer lies deeply rooted in Hironari’s lineage. His origins trace back to the influential Imibe clan (忌部氏), prominent figures responsible for imperial religious rituals in ancient Japan. Originally written as “忌部,” the name was changed to “斎部” in Hironari’s time, though the pronunciation remained the same. The Imibe clan wielded tremendous influence and originally descended from continental immigrant groups.

The clan brought diverse continental cultures into ancient Japan, primarily dispersed throughout western Japan, eventually migrating to Kansai. There, the clan became closely aligned with the imperial family in ancient Yamato, deeply involving themselves in politics. Their deity, Futodama (布刀玉命), played an important role in the famous myth of Amaterasu’s retreat into the cave (“Ama no Iwato-gakure,” 天岩戸隠れ), thus solidifying their claim of legitimacy. However, over time, the Imibe lost political influence amidst fierce power struggles within the imperial court, eventually disappearing from historical prominence. The group primarily responsible for their marginalization was the Nakatomi clan (中臣氏), which has been discussed several times in Shitsurae.

Although details have faded into historical obscurity, my research suggests that following the Taika Reform (大化の改新, 645), the Nakatomi’s ascendancy culminated during the reign of Emperor Tenmu (天武天皇, reigned 673–686), a key figure behind the Kojiki’s compilation. By the early ninth century, when Hironari lived, the Imibe clan had significantly weakened. Indeed, the Kogo Shui can be seen as an attempt by the ancient Imibe clan to reclaim legitimacy and counter the immense power of the Nakatomi clan, as this period already marked the Heian era.

As previously noted, the Heian period witnessed the rise of the Fujiwara clan, descended from the Nakatomi, dominating politics as regents. Although details from this era remain unclear, a clue lies in Hironari’s dedication of the Kogo Shui to Emperor Heizei (平城天皇, reigned 806–809). Heizei, son of Emperor Kanmu (桓武天皇, who founded Heian-kyo), lived through the turbulent transition from Heijo-kyo to Heian-kyo. Significantly, Heizei’s mother was Fujiwara no Otomuro (藤原乙牟漏, 760–790).

Tracing back further, Fujiwara no Otomuro’s father was Fujiwara no Yoshitsugu (藤原良継, 716–777), a high-ranking nobleman (公卿) of the Nara period, whose own father was Fujiwara no Umakai (藤原宇合, 694–737), the founder of the “Fujiwara Shikike” (藤原式家). Fujiwara no Umakai’s father, in turn, was the influential statesman Fujiwara no Fuhito (藤原不比等, 659–720), who laid the foundations for the Fujiwara clan’s subsequent golden age. Thus, following this golden age initiated by Fujiwara no Fuhito, Emperor Kanmu, whose authority and financial base had significantly weakened, could no longer disregard the growing influence of the Fujiwara clan, compelling him to select an empress from among their ranks. Indeed, Emperor Heizei, who succeeded Emperor Kanmu, also married an empress from the same Fujiwara Shikike branch, Fujiwara no Tarashiko (藤原帯子, ?–794).

My personal interpretation suggests Emperor Heizei was dissatisfied with being a puppet of the powerful Fujiwara and sought support from the Imibe clan, whose legitimacy dated back to ancient Japan, to challenge the Nakatomi-Fujiwara dominance. Indeed, Hironari reportedly authored the Kogo Shui in his eighties, possibly as part of a final attempt to restore imperial autonomy and revive the declining Imibe lineage amidst Fujiwara ascendance.

However, the era belonged undeniably to the Fujiwara. Despite their final efforts, the Imibe disappeared from central politics. Hironari, witnessing his clan’s end, wrote the Kogo Shui to reaffirm their ancient legitimacy.

Thus, was the ancient imperial legitimacy symbolized by regalia other than the established Sanshu-no-Jingi merely a claim by the marginalized Imibe? In fact, another influential ancient clan forced from central politics recorded evidence of different regalia. The next article will explore this alternative clan’s claim.