Details of the function are unknown. It doesn't seem to be known without downloading the app.
has added a "Hitsumabushi" function to the "Topic Nau" app that displays keywords that have become a hot topic on Twitter and other media in a ranking format. Details of the function are unknown. It is said that it can be used from the "Himamashita" function of the same application.
The app can be downloaded for free from the iTunes App Store
and Google Play.
Supported OS is iOS 4.3 and Android 2.1 or higher.
The "Hitsumabushi" function seems to exist
* April 1st is April Fool's Day. This article is a summary of what Yahoo has announced on April Fool's Day.