An image forming apparatus comprising: a housing having a discharge opening; a feeder configured to feed a medium; a developing unit configured to perform a first attachment process in which the developing unit attaches a luminescent toner to a first latent image that is formed on a basis of image data and the developing unit further configured to perform a second attachment process in which the developing unit attaches the luminescent toner to a second latent image that is formed on the basis of the image data; a transferring unit configured to perform a first transfer process in which the transferring unit transfers, onto a surface of the medium, the luminescent toner attached to the first latent image by the first attachment process, and the transferring unit further configured to perform a second transfer process in which the transferring unit transfers, onto the surface of the medium, the luminescent toner attached to the second latent image by the second attachment process to thereby cause the luminescent toner transferred onto the medium by the second transfer process to overlap a first luminescent image formed on the medium; and a fixing unit configured to perform a first fixing process in which the fixing unit fixes, to the medium, the luminescent toner transferred onto the medium by the first transfer process to thereby form the first luminescent image before the second transfer process, and the fixing unit further configured to perform a second fixing process in which the fixing unit fixes, to the medium, the luminescent toner transferred onto the medium by the second transfer process to thereby form a second luminescent image on the first luminescent image, with the second luminescent image overlapping the first luminescent image, wherein the second luminescent image has a same color as a color of the first luminescent image, the image data used in the second attachment process is the same as the image data used in the first attachment process, and the medium on which the first luminescent image and the second luminescent image are formed is discharged to outside of the housing from the discharge opening. a housing having a discharge opening; a feeder configured to feed a medium; a developing unit configured to perform a first attachment process in which the developing unit attaches a luminescent toner to a first latent image that is formed on a basis of image data and the developing unit further configured to perform a second attachment process in which the developing unit attaches the luminescent toner to a second latent image that is formed on the basis of the image data; a transferring unit configured to perform a first transfer process in which the transferring unit transfers, onto a surface of the medium, the luminescent toner attached to the first latent image by the first attachment process, and the transferring unit further configured to perform a second transfer process in which the transferring unit transfers, onto the surface of the medium, the luminescent toner attached to the second latent image by the second attachment process to thereby cause the luminescent toner transferred onto the medium by the second transfer process to overlap a first luminescent image formed on the medium; and a fixing unit configured to perform a first fixing process in which the fixing unit fixes, to the medium, the luminescent toner transferred onto the medium by the first transfer process to thereby form the first luminescent image before the second transfer process, and the fixing unit further configured to perform a second fixing process in which the fixing unit fixes, to the medium, the luminescent toner transferred onto the medium by the second transfer process to thereby form a second luminescent image on the first luminescent image, with the second luminescent image overlapping the first luminescent image, wherein the second luminescent image has a same color as a color of the first luminescent image, the image data used in the second attachment process is the same as the image data used in the first attachment process, and