It is used in combination with other apps "Icon X". This application alone does not work. Please refer to the information of "Pushing Icon X" for how to use it.

Click here for the recommended icon X
https://play.google.com/store/apps/details?id=com.fc2.blog9.zze128.iconx&hl=ja

supplement
When the background of the icon is displayed, the frame of the background of the icon at the lower right remains. In this case, please set not to display the background of the icon in the home application settings. It is a setting that unifies (forces) the background of the icon. If there is no applicable setting, please consider changing to another home application such as Microsoft launcer.

Home application setting example
Microsoft launcher
Home screen> Icon appearance> Make the app icon the same shape Turn off

Nova launcher
Appearance and operation ＞ Icon style ＞ Turn off Change the shape of the conventional icon