A medium (To) comprising a transparent base layer, an adhesive layer and a separation layer stacked on each other in a stacking direction, wherein the adhesive layer is disposed in at least a portion of an area located between the transparent base layer and the separation layer, wherein a plurality of regions are defined in the medium (To) along a first direction orthogonal to the stacking direction, wherein the plurality of regions comprise: a first region (D1a) in which a portion of the adhesive layer which is in contact with the separation layer comprises opposite end portions in a second direction orthogonal to each of the first direction and the stacking direction, and at least the opposite end portions are stickable; a second region (D2a, D2b, D3a) which is located on one side of the first region (D1a) in the first direction and in which a non-adhesive layer which is provided between the adhesive layer and the separation layer is non-stickable; and a third region (D3b) which is located on the one side of the second region (D2a, D2b, D3a) in the first direction and in which a portion of adhesive layer which is in contact with the separation layer is stickable, and wherein a longest length of the first region (D1a) in the second direction is less than a length of one of the second region (D2a, D2b, D3a) and the third region (D3b) in the second direction at a particular position in the first direction, characterized in that: the first region (D1a) comprises a first region edge (D1R, D1L) that is an edge of the first region (D1a) in the second direction; a mark (M6, M7) is provided in the one of the second region (D2a, D2b, D3a) and the third region (D3b) at the particular position in the first direction and at a position identical to a position of the first region edge (D1R, D1L) in the second direction; the first region (D1a) comprises a pair of first region edges (D1R, D1L), each as the first region edge (D1R, D1L), which are spaced apart from each other in the second direction; a pair of marks each as the mark are provided in the one of the second region (D2a, D2b, D3a) and the third region (D3b) at the particular position in the first direction so as to be spaced apart from each other in the second direction, each of the pair of marks, which is a straight-line mark, extends in the first direction; and each of the pair of first region edges (D1R, D1L) and a corresponding one of the pair of marks are aligned to each other in the first direction. a first region (D1a) in which a portion of the adhesive layer which is in contact with the separation layer comprises opposite end portions in a second direction orthogonal to each of the first direction and the stacking direction, and at least the opposite end portions are stickable; a second region (D2a, D2b, D3a) which is located on one side of the first region (D1a) in the first direction and in which a non-adhesive layer which is provided between the adhesive layer and the separation layer is non-stickable; and a third region (D3b) which is located on the one side of the second region (D2a, D2b, D3a) in the first direction and in which a portion of adhesive layer which is in contact with the separation layer is stickable, and the first region (D1a) comprises a first region edge (D1R, D1L) that is an edge of the first region (D1a) in the second direction; a mark (M6, M7) is provided in the one of the second region (D2a, D2b, D3a) and the third region (D3b) at the particular position in the first direction and at a position identical to a position of the first region edge (D1R, D1L) in the second direction; the first region (D1a) comprises a pair of first region edges (D1R, D1L), each as the first region edge (D1R, D1L), which are spaced apart from each other in the second direction; a pair of marks each as the mark are provided in the one of the second region (D2a, D2b, D3a) and the third region (D3b) at the particular position in the first direction so as to be spaced apart from each other in the second direction, each of the pair of marks, which is a straight-line mark, extends in the first direction; and each of the pair of first region edges (D1R, D1L) and a corresponding one of the pair of marks are aligned to each other in the first direction.