As a plugin developer you can use this plugin as dependency of your plugin by adding a dependency tag to your POM.
To add the latest version of this plugin as a maven dependency, use the following:
<dependency>
<groupId>jp.ikedam.jenkins.plugins</groupId>
<artifactId>update-sites-manager</artifactId>
<version>91.v38ff0407cb_a_d</version>
</dependency>