ongekigen retsurai

It is a spear-like weapon used by Kamen Rider Zanki. After his retirement, Kamen Rider Todoroki inherited it.
When the Ongekishin Raigou is attached, the blade unfolds, transforming it into an electric guitar. By strumming it while it remains impaled on a Makamou, it purifies the evil energy that comprises the target.