Abstract: According to embodiments a memory system is connectable to a host which includes a host controller and a host memory including a first memory area and a second memory area. The memory system includes an interface unit, a non-volatile memory, and a controller unit. The interface unit receives a read command and a write command. The controller unit writes write-data to the non-volatile memory according to the write command. The controller unit determines whether read-data requested by the read command is in the first memory area. If the read-data is in the first memory area, the controller unit causes the host controller to copy the read-data from the first memory area to the second memory area. If the read-data is not in the first memory area, the controller unit reads the read-data from the non-volatile memory and causes the host controller to store the read-data in the second memory area.