The Seijou Girls Academy's Kendo Club is traveling to Shoushinji for summer training camp. Near there is an island, Urashima, where a demon extermination took place long ago.
It happens that this summer something related to that demon extermination is also going to take place as the captain of the team, Osanai Syouko finds a young girl washed up on the beach...

This is the official comic based on the PS2 game Aoishiro which is a sister game to Akaiito.