A medium (To, T) to be mounted in a printer, to be conveyed in a conveying direction and to be printed with the printer, the medium (To, T) comprising: a release material having a strip-like shape including a long side parallel to a first direction and a short side parallel to a second direction, the first direction being along the conveying direction, the second direction being orthogonal to the first direction; a first slit provided in the release material and having a square shape including a first side, a second side, a third side, and a fourth side, the first side and the second side being parallel to the first direction and juxtaposed in the second direction in this order, the third side and the fourth side being parallel to the second direction and juxtaposed in the first direction in this order; a first print label fixed to the release material so as to span across both the first side and the second side; a second slit provided in the release material, the second slit being provided on one side of the first slit in the first direction and having a square shape including a fifth side, a sixth side, a seventh side, and an eighth side, the fifth side and the sixth side being parallel to the first direction and juxtaposed in the second direction in this order, the seventh side and the eighth side being parallel to the second direction and juxtaposed in the first direction in this order; a second print label fixed to the release material so as to span across both the fifth side and the sixth side; and a mark provided on the release material, the mark having an upstream edge in the conveying direction positioned downstream from the fourth side and a downstream edge in the conveying direction positioned upstream from the seventh side, wherein the first print label and the second print label are arranged discretely along the first direction. a release material having a strip-like shape including a long side parallel to a first direction and a short side parallel to a second direction, the first direction being along the conveying direction, the second direction being orthogonal to the first direction; a first slit provided in the release material and having a square shape including a first side, a second side, a third side, and a fourth side, the first side and the second side being parallel to the first direction and juxtaposed in the second direction in this order, the third side and the fourth side being parallel to the second direction and juxtaposed in the first direction in this order; a first print label fixed to the release material so as to span across both the first side and the second side; a second slit provided in the release material, the second slit being provided on one side of the first slit in the first direction and having a square shape including a fifth side, a sixth side, a seventh side, and an eighth side, the fifth side and the sixth side being parallel to the first direction and juxtaposed in the second direction in this order, the seventh side and the eighth side being parallel to the second direction and juxtaposed in the first direction in this order; a second print label fixed to the release material so as to span across both the fifth side and the sixth side; and a mark provided on the release material, the mark having an upstream edge in the conveying direction positioned downstream from the fourth side and a downstream edge in the conveying direction positioned upstream from the seventh side, wherein the first print label and the second print label are arranged discretely along the first direction.