"Battery Remains" is a widget. The first sound mic (Bocaro/Bocaroide) is a battery that is changing in the same way as the battery is consumed.
『電池残量表示ウィジェット.初音ミク[ボカロ/ボーカロイド]』～電池消費にあわせてミクの姿が変化！節電管理もできる～