His imina (posthumous name) is '時存' ('Tokihiro' or 'Tokiari') and his formal nanori (self-introduction, announcement of candidature) is TAIRA no Tokihiro/Tokiari.
諱は「時存」（「ときひろ」「ときあり」）であり、正式な名のりは平時存(たいらのときひろ/ときあり)。