This is a man's cotton kimono called a yukata, worn in summer at festivals or casual events. Same construction as a kimono, just in cotton. Men's yukata typically feature a small repeated pattern in blue and white.
The patterning on this yukata reminds us of hashtags - there are so many crossed lines. Many shades of blue and gray layered on top of each other. Hope to see this on social media adorning its new owner! There is a 4" tuck at the waist - this is how the yukata was shortened - with stitching that can be easily removed to extend the length if desired (see photo). See the video below for details on how to put on a man's yukata with a simple sash.