1. An information processing device comprising: a memory and one or more processors coupled to the memory for executing: a communication unit configured to transmit textual information; a schedule storage unit configured to store schedule information; a keyword storage unit configured to store multiple keywords that are classified into multiple categories; a keyword extraction unit configured to extract keywords from the textual information transmitted by the communication unit on the basis of the keywords stored in the keyword storage unit, and specify one category corresponding the extracted keywords when extracting a keyword which was classified into a plurality of categories based on a position thereof and relationships to other words in the textual information; a schedule information creation unit configured to create new schedule information or revised schedule information which causes the schedule information stored in the schedule storage unit to be updated, based on the keywords extracted by the keyword extraction unit and the categories of the extracted keywords; and a schedule updating unit configured to store the new schedule information into the schedule storage unit, and update the schedule information stored in the schedule storage unit with the revised schedule information.