An object of the present invention is to discover a substance with sweetness independent of pH and to provide a novel composition with sweetness characterized by containing the substance. Provided are: an NAS variant characterized by having sweetness independent of pH in the case of combination with a polypeptide NBS variant by causing substitution mutation or deletion mutation in one or several amino acids out of the amino acid residues constituting a polypeptide NAS; an NBS variant characterized by having sweetness independent of pH in the case of combination with a polypeptide NAS variant by causing substitution mutation or deletion mutation in one or several amino acids out of the amino acid residues constituting a polypeptide NBS; a diner comprising a combination of the NAS variant and the NBS variant; a recombinant vector containing a gene encoding the NAS variant and a gene encoding the NBS variant; and a transformant containing the vector.