A case of left leg necrotizing fasciitis caused by streptococcus pyogenes in a healthy Japanese man

•We experienced a case of necrotizing fasciitis (NF) due to Group A streptococcus in a healthy Japanese man.•Cutaneous manifestations with NF can be initially minimal.•It is important to recognize that one of the characteristic symptoms of NF is severe pain out of proportion.•When NF is suspect, emergent surgical exploration and debridement are required.