Five-membered heterocyclic derivative

A compound represented by formula (I), a salt of the compound, or a solvate of the compound or the salt:

• wherein the group represented by formula (1):
• is any of the groups represented by formula (a) to (c):
• (wherein Ar1 and Ar2 each independently represent a 6-membered aromatic heterocyclic group which may have a substituent or a phenyl group which may have a substituent;
• and R2 represents a group selected from among a hydrogen atom, a halogeno group, a hydroxyl group, a lower alkoxy group, and a lower alkyl group which may have a substituent);
• X represents a carbonyl group or a thiocarbonyl group;
• and
• Y represents a group represented by formula (2):
• (wherein the ring structure A represents a 4- to 7-membered ring which may have, in addition to N shown in formula (2), one hetero atom selected from among N, O, and S;
• and the ring structure A may have a substituent represented by R1, wherein R1 represents 1 to 4 groups, which are identical to or different from one another, selected from among a hydroxyl group, a cyano group, an oxo group, a halogeno group, a lower alkyl group which may have a substituent, a lower alkoxy group, an aralkyloxy group, a lower thioalkoxy group, a lower alkoxycarbonyl group, an aralkyloxycarbonyl group, a lower acyl group, a carboxyl group, a hydroxyiminocarbonyl group, an alkoxyimino group, a lower alkylsulfonyl group, an amino group which may have a substituent, a carbamoyl group which may be a substituted by a lower alkyl group, an aminosulfonyl group which may be substituted by a lower alkyl group, a 3- to 6-membered spiro-alicyclic alkyl group which may have a substituent, and a 4- to 7-membered alicyclic heterocyclic group which may have a substituent).