These Pajamas are Japan sizing.
Please check the following Japan size to US size conversion chart.
Garment size
US XXS (JP XS)
Length: 69 cm, Shoulder width: 45.5 cm, Chest: 106 cm, Sleeve length: 54 cm, Inseam: 68.5 cm, Waist: 63 cm
US XS (JP S)
Length: 71 cm, Shoulder width: 47 cm, Chest: 110 cm, Sleeve length: 55 cm, Inseam: 70 cm, Waist: 67 cm
US S (JP M)
Length: 73 cm, Shoulder width: 48.5 cm, Chest: 114 cm, Sleeve length: 56 cm, Inseam: 71.5 cm, Waist: 71 cm
US M (JP L)
Length: 75 cm, Shoulder width: 50 cm, Chest: 118 cm, Sleeve length: 57 cm, Inseam: 73 cm, Waist: 75 cm
US L (JP XL)
Length: 77 cm, Shoulder width: 52 cm, Chest: 124 cm, Sleeve length: 58.5 cm, Inseam: 75 cm, Waist: 81 cm
US XL (JP XXL)
Length: 79 cm, Shoulder width: 54 cm, Chest: 130 cm, Sleeve length: 60 cm, Inseam: 77 cm, Waist: 87 cm