Mobile Joy or MobileJOY (モバイルジョイ) is a bonus option in various Koei titles made exclusive for Japanese cellphone services. By registering a Koei product with a respective cell phone service, players can unlock bonus items or features for their purchased game. Character wallpapers, voiced lines, or select songs can be made available for the user's cellphone. In order to perform a Mobile Joy transfer, the requiring steps must be taken: