Len Kagamine from Vocaloid

The image is of a person dressed in a costume, likely for cosplay or a themed event. The person has short blonde hair and is wearing a white sleeveless top with red sleeves that are tied at the waist. There appears to be some embroidery on the front of the shirt, but it's not clear what it says. The background of the image is out of focus, but there appear to be several people sitting in chairs behind the person in the foreground. It looks like they may be attending a convention or other event where costumes are common.