A coupler includes a first hook assembly comprising a first hook adapted to receive a first associated attachment pin and a second hook assembly comprising a second hook adapted to receive a second associated attachment pin. The optical connector includes a housing body portion to be connected to a mating optical connector and a bending guide portion. The inlet opening has a first coupling part for coupling the rectal catheter into fluid communication with the bag, and the bag has a second coupling part inside it for mating the first coupling part. Only those regions whose areaperimeter ratio is less than a certain threshold are kept for closest-to-radial-based-function filtering to estimate colors from neighboring pixels to fill in the missing data regions. As a result, random access in which desired nonvolatile memory cells are accessed sequentially is enabled in a nonvolatile semiconductor memory having a pipeline function for performing plural read operations in parallel.