Recording medium, playback device, and playback method

A playback device comprising:

• a readout unit that reads out a main video stream and a sub-video stream that are recorded in a recording medium, the main video stream being a main video that has been encoded, and the sub-video stream being a sub-video that is encoded and that is to be superimposed on the main video and displayed;
• and
• a playback unit that plays the main video stream and the sub-video stream that have been read out,
• wherein the sub-video stream includes a plurality of sets, each set comprising a first sub-video stream for a first luminance dynamic range and a second sub-video stream for a second luminance dynamic range, which is wider than the first luminance dynamic range,
• wherein, in the recording medium, a first database specifying the first sub-video stream and a second database specifying the second sub-video stream are recorded, and
• wherein, in a same set in the plurality of sets, a registration order of the first sub-video stream in the first database and a registration order of the second sub-video stream in the second database are same.