"Keage" literally means to kick up something, and it is supposedly derived from a historical event.
In autumn Angen 3 (1177) Ushiwaka-maru (Minamoto no Yoshitsune, a feudal warlord in Heian Era, before coming of age) passed through this area on his way to Oshu (current Tohoku district), and a horse of Heike warrior accidentally kicked the water in a puddle on to Ushiwaka-maru.