Displaying pieces of data includes displaying a tree structure on a display device, identifying, in response to a first node being selected from among nodes constituting the displayed tree structure, all nodes connected to the first node in a high-order direction and a low-order direction as a first node group, and identifying, in response to a second node being selected, the second node not being included in the first node group, all nodes connected to the second node in the high-order direction and the low-order direction as a second node group. The second node moves toward the first node according to an operation. A node not to be displayed is determined according to a rule and movement of the second node group. A display device is instructed to display the first node group and the second node group close to each other omitting display of the determined node.