1. An image forming apparatus, comprising: a failure prediction unit configured to prepare an index value indicating a condition of the image forming apparatus based on multidimensional signal, obtained by monitoring the image forming apparatus, and to compare the index value with a first threshold value to predict a failure mode of the image forming apparatus; an image identification unit configured to identify an image abnormality based on the failure mode predicted by the failure prediction unit, an identified image abnormality being an abnormality predicted to appear at a given time later if an image forming operation conducted under a condition predicted by the index value is executed; a simulated-image generating unit configured to generate a simulated image including the identified image abnormality; and an output unit configured to output the simulated image.