11. The character input prediction apparatus according to claim 1 , further comprising: a second operation input unit configured to obtain information of a second character input operation that is performed by the user using the character key layout display; a second indication movement detection unit configured to detect a second indication position and a second indication direction in the character key layout display from the information of the second character input operation, the second indication position showing a position of the second character input operation, and the second indication direction showing a movement direction of the second character input operation; a second filter generation unit configured to determine a second character range in the character key layout display using the second indication position, the second indication direction, and the character key layout, the second character range being located in the second indication direction with the second indication position as the base point; and a filter synthesis unit configured to extract a third character range that is included in both the first character range and the second character range, wherein the dictionary search unit is configured to search the plurality of candidate character strings included in the dictionary, for the predictive character string that includes any character included in the third character range.
11. The character input prediction apparatus according to claim 1 , further comprising: a second operation input unit configured to obtain information of a second character input operation that is performed by the user using the character key layout display; a second indication movement detection unit configured to detect a second indication position and a second indication direction in the character key layout display from the information of the second character input operation, the second indication position showing a position of the second character input operation, and the second indication direction showing a movement direction of the second character input operation; a second filter generation unit configured to determine a second character range in the character key layout display using the second indication position, the second indication direction, and the character key layout, the second character range being located in the second indication direction with the second indication position as the base point; and a filter synthesis unit configured to extract a third character range that is included in both the first character range and the second character range, wherein the dictionary search unit is configured to search the plurality of candidate character strings included in the dictionary, for the predictive character string that includes any character included in the third character range. 12. The character input prediction apparatus according to claim 11 , wherein the filter synthesis unit is further configured to determine, as the third character range, a range that is included in the first character range and is located in a direction toward the first indication position with the second indication position as the base point, in the case where the position of the first character input operation moves and a movement amount of the position of the second character input operation is equal to or less than a predetermined threshold.