An in-situ image sensor (ISIS) capable of recording moving images at a rate of 1,000,000 pps is proposed, with the following characteristics. (1) The CCD strips for image signal storage are elongated vertically and run below several pixels, unlike existing ISIS implementations. This unidirectional charge transfer reduces the number of layers of wiring required to drive the charges. (2) The CCD strips perform the dual roles of image signal storage and readout. In the image capture phase, the electric potential of the boundary element of each CCD storage strip is kept at a constant high value, and the charge transferred to the element is drained from the image sensor. This defines the number of elements available for storage. In the readout phase, the potential of the boundary element is controlled so as to allow charge transfer downward through the remainder of the CCD strips as in usual CCD operation. The unidirectional transfer and the dual-role CCD make the proposed sensor the simplest and, therefore, the best approach to ISIS, contributing to a higher frame rate, a greater number of sequentially-stored frames, and better quality of reproduced images. In a practical design, space is required for the gate connecting each photosensor to its CCD strip. To produce an interline sensor, a photodiode can be fabricated in the knife-shaped slit between meandering CCD strips. A micro-cylindrical lens could increase the area ratio of the photodiode to around 20%.