The Bugster Virus (バグスターウイルス Bagusutā Uirusu) are the foot soldiers of the in Kamen Rider Ex-Aid. The Bugster Virus initially start off as a micro-sized virus infecting humans. Bugster-infected may either show symptoms akin to normal human illnesses, or even show no symptoms at all. The Bugster Virus begins to develop inside an infected human as they begin to get stressed out, until the human is physically taken over and covered by the virus, transforming them into a gigantic virus-like Bugster Union. It appears that some games, like Bakusou Bike, also employ neutral Bugster Viruses.