Amatsumikaboshi is a god of stars (Shinto) appearing in Japanese mythology. Other names are Amenokagaseo and Kagaseo.
It does not appear in Kojiki (The Records of Ancient Matters), but appears only in the conquest of Ashihara no nakatsukuni in Nihonshoki (Chronicles of Japan). In the main body, Futsunushi and Takemikazuchi suppressed Kunitsu Kami (gods of the land) entirely, even finishing off plants and stones, but Kagaseo, the god of stars, solely disobeyed, so Takehatsuchi (Shitorigamitakehazuchi no Mikoto) was dispatched for conquest. In Arufumi Vol. 2 (supplement volumes of explanatory notes in Nihonshoki), it is referred to as Amatsu Kami (god of heaven), and Futsunushi no Kami and Takemikazuchi no Mikoto say they would first kill an evil god called Amenokagaseo, otherwise known as Amatsumikaboshi in Takamanohara (plain of high heaven), before the conquest of Ashihara no nakatsukuni.
Atsutane HIRATA claims the 'mika' in the shinmei (name of god) means 'fierce,' and that Amatsumikaboshi represents Venus. The word 'kaga' means 'shine' and is believed to describe the stars shining.
Gods deifying stars and the moon are seen all over the world, and gods of stars in particular are sometimes treated as shusaijin (main enshrined deities). However, in Japanese mythology, the god of stars is depicted as a god who should be brought to submission, or 'matsurowanu kami' (disobedient god). Regarding this, some say it refers to the fact that there was a tribe which worshipped the god of stars, and who did not obey the Yamato sovereignty (the ancient Japan sovereignty).
Many of the Hoshi-jinja Shrines and Hoshinomiya-jinja Shrines nationwide enshrine Amatsumikaboshi.
Omika-jinja Shrine in Hitachi City, Ibaraki Prefecture enshrines Takehazuchi no Mikoto, who brought Amatsumikaboshi to submission. According to the shrine's biography, Mikaboshikakaseo (Amatsumikaboshi) took up residence in Mt. Omika of Hitachi Province and reigned Togoku (the eastern part of Japan). The Shukkonseki Stone which constitutes the holly precincts of Omika-jinja Shrine is believed to be the stone where the Aramitama (god's rough soul) of Mikaboshikakaseo was contained. According to one theory, since the curse of Amatsumikaboshi continued after being contained by Takehazuchi no Mikoto, Omika-jinja Shrine enshrining Takehazuchi no Mikoto was built to quiet this down.
For being the last god to resist the conquest of Ashihara no nakatsukuni in Nihonshoki, it is at times viewed as the same god as Takeminakata. Additionally, it is sometimes viewed as an incarnation of Myoken Bosatsu who deified the polar star.