In rural areas of Hakusan, Ishikawa Prefecture, Japan, the local monkey population has been causing damage to sweet potato farms and surrounding lands. To address this issue, a prototype system has been developed to assist farmers in protecting their fields during the months of September through November in both 2022 and 2023. The system is based on deep-learning models utilizing the you-only-look-once (YOLO) algorithm to classify and localize images of the local monkeys simultaneously. Real-time detection of live monkeys is possible using a Streaming Protocol Camera (RTSP), with the system automatically notifying farmer group members via the Line application when a monkey is detected. The system was trained using data collected from trap cameras placed around the sweet potato fields and successfully operated on a Windows PC with 32 GB RAM, a 64-bit Operating System, and an Intel(R) Core(TM) i9-9900K processor with an Nvidia GeForce RTX 3080 10 GB graphics processing unit (GPU). Performance metrics based on k-fold cross-validation showed precision, recall, and AP@0.5 values of 0.7310, 0.8462, and 0.7421, respectively, indicating high accuracy and classification performance using a real-time streaming camera. By alerting farmers in advance, the system can prevent damage caused by monkeys in sweet potato fields.