First get you a plain dark blue t-shirt

And some white shorts

Heres the arm bands.
Get your white long sleeve shirt, measure from your elbow to your wrist, cut at the elbow.
Take your dark blue fabric and cut 4 thin strips,
take each strip and place over top of the end of the cut sleeve and sew around.

Heres the leg bands.
Take the white shirt and cut the rest of the sleeve off at the shoulder.
Cut 4 more strips from the dark blue fabric and do so as in step 3.

Take your red paint and draw a sideways half moon

Take your white paint and draw the image shown underneath the red half moon

And your ready to do some cosplaying!