Society 5.0 enables a highly developed IT society. Then, AI and big-data applications sometimes accept their inaccurate computation results. The imperfect computing exploits the design trade-off among accuracy, throughput, and energy. The above applications usually work in data centers and supercomputers, and the communication overhead between nodes becomes the performance bottleneck. This study reduces the margin of circuits so that the high-bandwidth low-latency optical communication is obtained with a moderately lowered bit error rate. Then, we present parallel computation and algorithms for such an environment.