Dearest Monster is an innovative tool for detecting harvest time, controlling temperature, humidity, and repelling pests in oyster mushrooms based on the Internet of Things. The innovation of this tool consists of 9 main parts, such as NodeMCU ESP8266, Laser Module, LDR Sensor, DHT-11 Sensor, ultrasonic wave transmitter, Relay Module, 12volt DC Fan, 12volt DC Pump and buzzer.