Akagi Daimyojin is a mountain deity that represents the deification of Mount Akagi itself in the former Kozuke Province (present-day Gunma Prefecture). The caldera lakes at the summit, Lake Ono and Lake Kono, are revered as its physical embodiment (shintai). Since ancient times, it has been deeply worshipped as a god of the mountain, water, and agriculture[1]. It is frequently identified with Toyoki-irihiko-no-mikoto, an early regional governor appearing in classical mythology, or with Oanamuchi-no-mikoto (Okuninushi). Concurrently, there exist traditions that revere it as the goddess "Akagi-hime," acting as a protector of women[1]. With about three hundred branch shrines centered around the Kanto region, the grand head shrines of Akagi Shrine are said to be Miyosawa Akagi Shrine on the mountainside and Daido Akagi Shrine at the summit, preserving the widespread influence of the Akagi faith to this day[1]. In the realm of folklore, Akagi Daimyojin is widely known for the "Battle of the Gods" (Shinsen), where it fought against the deity of Mount Futarasan in the neighboring Shimotsuke Province (present-day Tochigi Prefecture) over the territory of Lake Chuzenji, famously transforming into a giant centipede (O-mukade) during the conflict[2].
Folklore & Legends
The most renowned legend is the "Battle of the Gods" against the deity of Mount Futarasan in Nikko. The two deities fought over the dominion of Lake Chuzenji, and unable to reach a settlement, they finally resorted to armed conflict. According to the standard narrative from the Nikko side,[2] the deity of Mount Futarasan transformed into a giant serpent, while the deity of Mount Akagi became a giant centipede. They clashed violently at what is now Senjogahara (literally, "Battlefield Moor")[2]. The place name "Senjogahara" stems from this mythological battle; it is said the area was once called Akanumagahara ("Red Swamp Moor") because the spilled blood dyed the fields red[2]. Initially, the Akagi faction held the upper hand. However, the struggling Futarasan deity, acting on the advice of Kashima Daimyojin, summoned Sarumaro, a master archer from the Oshu region. Sarumaro's arrow pierced the left eye of the giant centipede, forcing the Akagi faction to retreat into the mountains[2].
Conversely, the hot spring discovery legend passed down in Oigami Onsen of Numata City, Gunma Prefecture, features a reversal of roles. Here, the deity of Mount Akagi is portrayed as the giant serpent, while the Nikko deity is the giant centipede[3]. Wounded by an arrow, the serpent god of Akagi pulled out the projectile and thrust it into the foothills, causing hot water to gush forth. The serpent healed its wounds with this spring water and subsequently drove away its enemy. It is said that the name "Oigami" (meaning "pursuing god") eventually evolved into the current "Oigami" (meaning "old god"). Even today, the "Great Serpent Festival" is held every May, with a mikoshi (portable shrine) of a giant serpent parading through the hot spring town[3]. As such, the victor and the chosen avatars differ by region. The coexistence of divergent legends—one where Akagi wins and another where it loses—vividly reflects the fierce rivalry between mountain deity cults spanning ancient provincial borders[3].
Akagi Daimyojin is the deified embodiment of the entirety of Mount Akagi, which towers over the northern edge of the Kanto Plain. Rather than a singular anthropomorphic god, it strongly exhibits the nature of a "deity of place" that governs the mountains, swamps, forests, and springs. Consequently, it has been depicted in multifaceted ways over time—associated with Toyoki-irihiko-no-mikoto, Oanamuchi-no-mikoto, or even the goddess Akagi-hime. Its transformation into a giant centipede (or serpent) in the Battle of the Gods represents its fierce, combative aspect, forming a stark contrast to its gentle demeanor as a deity of agriculture and water during times of peace. The fact that real geographical locations like Senjogahara, Akanuma, and Oigami are all narrated as remnants of this divine battle suggests how deeply these legends are rooted in the local landscape. The cycle of tales featuring the Nikko deity as an adversary is essentially a mythologization of the border disputes between the former provinces of Kozuke and Shimotsuke. The variations in avatars and outcomes (whether Akagi is the centipede or the serpent, the victor or the vanquished) are direct reflections of the regional pride embedded in each area.
Character Profile
This section is our own creative profile for storytelling. It is not historical fact or scholarship.
Majestic and reticent, possessing a strong sense of pride in protecting its territory and water sources. While it shows an unyielding spirit toward neighboring deities, it pours deep affection upon the people living at the foot of the mountain.
Transformation into a giant centipede or serpentDominion over mountains and water sourcesProtection of agriculture and the blessing of bountiful harvestsManifestation of divine wrath against those who invade its territory
Weaknesses
Arrows shot by a master archer (its left eye was pierced during the Battle of the Gods). A stubborn streak that makes it willing to wage war over boundary disputes.
Habitat
The summit of Mount Akagi, Lake Ono, Lake Kono, and the mountainside Akagi Shrine. Also the Senjogahara area in Nikko, the stage for the Battle of the Gods.
The diagram below is a diagnostic evaluation chart for Akagi Daimyojin, the Deity Ruling Mount Akagi. The higher the value of each item, the stronger that characteristic is expressed.
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