Inkjet ink, ink set, ink medium set, and printing medium

An inkjet ink comprising a pigment, a water-soluble organic solvent, and an organic compound excluding the pigment and the water-soluble organic solvent, wherein

• a log P value of the water-soluble organic solvent is less than 1.258;
• an interface tension of the organic compound with respect to biaxially oriented polypropylene (OPP) is less than 20.7 mN/m, where the interface tension at 25° C. between an OPP film and a mixture of 1 part by mass of the organic compound, 9 parts by mass of 1,4-butanediol, and 90 parts by mass of purified water, as determined by contacting the mixture with the OPP film, is defined as the interface tension of the organic compound with respect to OPP;
• a value of (B)/(A) is 0.01 to 0.50, where (A) represents a total mass of the water-soluble organic solvent contained in the inkjet ink, and (B) represents a total mass of the organic compound;
• and
• the inkjet ink has a surface tension of less than 33.7 mN/m at 25° C.