Wing morphological variations are described here for the lycaenid butterfly Tongeia fischeri. A landmark-based geometric morphometric approach based on wing venation of 197 male and 187 female butterflies collected in Japan was used to quantify wing size and shape variations between sexes and among populations. Sexual dimorphism in wing size and shape was detected. Females had significantly larger wings than males, while males showed a relatively elongated forewing with a longer apex and narrower wing tornus in comparison to females. Intraspecific variations in wing morphology among populations were revealed for the wing shape, but not wing size. Distinct wing shape differences were found in the vein intersections area around the distal part of the discal cell where median veins originated in the forewing and around the origin of the CU1 vein in the hindwing. In addition, phenotypic relationships inferred from wing shape variations grouped T. fischeri populations into three groups, reflecting the subspecies classification of the species. The spatial variability and phenotypic relationships between conspecific populations of T. fischeri detected here are generally in agreement with the previous molecular study based on mitochondrial and nuclear sequences, suggesting the presence of a phylogenetic signal in the wing shape of T. fischeri, and thus having taxonomic implications.