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].