Seidaimyojin (清大明神) is a lesser-known kami enshrined at certain shrines in Japan, associated in popular tradition with victory and success in contests, including sports and competitive endeavors. As with many localized "myojin" titles, the name reflects an honorific designation for a manifest deity rather than a figure with an extensive independent mythological record. Devotees have historically sought favor from Seidaimyojin before matches or challenges, though detailed doctrinal or historical documentation about this particular deity remains limited.