Ink composition and ink set

An ink composition, comprising:

• a dye (M-2) represented by Formula (M-2);
• a dye (Y-1) represented by Formula (Y-1);
• an alkylene oxide adduct of acetylene glycol having a main chain of 12 or more carbon atoms;
• acetylene glycol having a main chain of 10 or more carbon atoms;
• and
• a polyoxyalkylene alkyl ether,
• wherein the content ratio A of the dye (M-2) and the dye (Y-1) (the dye (M-2):
• the dye (Y-1)) is 1.25:1 to 4.75:1.
• (In the formula (M-2), AM2 represents a 5-membered heterocyclic group;
• each of BM21 and BM22 represents —CRM21═ or —CRM22═, or any one of BM21 and BM22 represents a nitrogen atom and the other thereof represents —CRM21═ or —CRM22═;
• RM23 and RM24 each independently represent a hydrogen atom, an aliphatic group, an aromatic group, a heterocyclic group, an acyl group, an alkoxycarbonyl group, an aryloxycarbonyl group, a carbamoyl group, an alkylsulfonyl group, an arylsulfonyl group, or a sulfamoyl group, and may further have a substituent;
• GM2, RM21, and RM22 each independently represent a hydrogen atom, a halogen atom, an aliphatic group, an aromatic group, a heterocyclic group, a cyano group, a carboxyl group, a carbamoyl group, an alkoxycarbonyl group, an aryloxycarbonyl group, an acyl group, a hydroxy group, an alkoxy group, an aryloxy group, a silyloxy group, an acyloxy group, carbamoyloxy group, heterocyclic oxy group, an alkoxycarbonyloxy group, an aryloxycarbonyloxy group, an amino group substituted with an alkyl group, aryl group or heterocyclic group, an acylamino group, a ureido group, a sulfamoylamino group, an alkoxycarbonylamino group, an aryloxycarbonylamino group, an alkyl- or aryl-sulfonylamino group, a nitro group, an alkyl- or aryl-thio group, an alkyl- or aryl-sulfonyl group, an alkyl- or aryl-sulfinyl group, a sulfamoyl group, a sulfo group, or a heterocyclic thio group, and may be further substituted;
• and RM21 and RM23 or RM23 and RM24 may be bound to form a 5- or 6-membered ring.)
• (In the formula (Y-1), R4 represents a substituent;
• R5 represents —OR6 or —NHR7 (each of R6 and R7 represents a hydrogen atom or a substituent);
• X3 represents a divalent linking group;
• n0 is 0 or 1;
• Ar3 represents a divalent heterocyclic group;
• and Ar4 represents an alkyl group, an aryl group, or a triazine group.)