#hem tuck

Much wow, very gender for this outfit, with moon-patterned yukata (worn shirippashori) and modern obi worn over Western shirt and pants.

Fun modern styling, taking advantage of kimono shirippashori (back tuck, which raises kimono hem) to unveiled a lovely patterned yukata. This style can easily be mimicked by using a modern skirt or a patterned susoyoke (wrap skirt used as underskirt in kimono fashion):

Shirippashori is usually mostly seen on men, as in traditional kimono fashion rich demure and idle women should not“flash” their undergarment like this. Yet in the past it was used by workers and travelers of both sex when freedom of movement was require: 

Genderfluid modern kimono styling by Fumi Saito, featuring a woman kimono worn otoko-poi (man styled) over wide pants.

The back hem tuck is called shirippashori and was historically worn by both sex of the working class and by travelers.

OP also made an nice step by step video (another version over a shirt here), I captured stills to better explain what is going on if you also wanna try this style:

1) Woman kimono (unlined) put upon tshirt+wide pants

2) Kimono lenght is adjusted to reach foot, excess fabric is blousing on top

3) Himo/cord is set to keep the kimono close at this lenght

4) OP is forming an ohashori, the waist fold neatly smoothing excess fabric up top (1-4 steps are how women put on their kimono)

5) Instead of placing a himo on the waist like a woman would, OP ties it low on his hips (=man style)

6+7) Back hem is raised up and tucked under this himo, to for a shirihashori

8) a kaku obi is tied low on the waist, as per usual in man fashion