I wanted to think of a cool name for this product and spent a total of 1 minute before I came up with... "Long Shirt" (Blue). Goes well with the and birthday suit - but only wear the birthday suit at home please.
You can tie the belt Japanese style at the back which will make the waistline look slim. If you are buttoning up the shirt then you will only manage that with S bust.|ロングシャツはやお家でごろごろ誕生日スーツに似合います。