A novel facultative anaerobic, Gram-stain-negative coccus, designated strain ChDC B345(T), was isolated from human pericoronitis lesion and was characterized by polyphasic taxonomic analysis. The 16S ribosomal RNA gene (16S rDNA) sequence revealed that the strain belonged to the genus Streptococcus. The 16S rDNA sequence of strain ChDC B345(T) was most closely related to those of Streptococcus mitis NCTC 12261(T) (99.5%) and Streptococcus pseudopneumoniae ATCC BAA-960(T) (99.5%). Complete genome of strain ChDC B345(T) was 1,972,471bpin length and the G+C content was 40.2mol%. Average nucleotide identity values between strain ChDC B345(T) and S. pseudopneumoniae ATCC BAA-960(T) or S. mitis NCTC 12261(T) were 92.17% and 93.63%, respectively. Genome-to-genome distance values between strain ChDC B345(T) and S. pseudopneumoniae ATCC BAA-960(T) or S. mitis NCTC 12261(T) were 47.8% (45.2-50.4%) and 53.0% (51.0-56.4%), respectively. Based on these results, strain ChDC B345(T) (=KCOM 1679(T)=JCM 33299(T)) should be classified as a novel species of genus Streptococcus, for which we propose the name Streptococcus gwangjuense sp. nov.