The Flag of Adachi is the official symbol representing Adachi, one of the 23 Special Wards of Tokyo, Japan. It features a white field divided diagonally by a blue stripe, starting from the hoist side corner and extending to the fly side corner at approximately 45 degrees. At the intersection of the diagonal line and the upper half of the flag, there is a red circle with a diameter equal to one-tenth of the length of the shorter flag side. The red circle symbolizes the sun, a common motif in Japanese flags, while the blue stripe represents the Sumida River that flows through Adachi Ward. The design of the Adachi flag reflects its historical and cultural connection to this iconic waterway.