1. A memory controller comprising: circuitry configured to acquire a distribution of threshold voltages of a plurality of memory cells from a nonvolatile memory, the nonvolatile memory including the plurality of memory cells; compare a characteristic value and a condition, and identify a malfunction state occurring in the nonvolatile memory based on a result of the comparison, the characteristic value indicating a shape characteristic of the distribution, the condition defining a range of an obtainable characteristic value in plural types of the malfunction states; and set a read voltage when data is read out of the nonvolatile memory to a voltage value corresponding to a type of the malfunction state.