Takuroubi is a fire spirit of Japanese lore that originates from Hiroshima and Okayama. It appears on beaches at night, from summer to autumn, as spheres of fire. They're well-known among the sailors from the Inland Sea. One legend says that sailors have seen two flickering balls of fire floating above the sea, looking like they're competing with each other, but never talked about them. This is why they are also known as Kurabebi, which comes from kuraberu - to compare/compete.
Another legend states that two women who suffered untimely deaths turned into two stones called Kyoujorou/Keijourou and Chikushijorou. Their souls eventually turned into Takuroubi.