Re: patching hakama
If the tear is really a tear, rather than a hole, I would start by lining up the edges and machine stitching with a zigzag stitch (fairly wide, say 3/4 if 4 is widest, and very short stitches, that is, many stitches per inch but not so short that the fabric won't feed well). Generally 3 parallel lines of zigzag, starting and ending 3/4" from the tear, will be good initial damage control for underneath the patch.
For the patch, select a fabric to closely match the color and weave of the hak. I would cut it so the patch extends 2" from the tear in each direction, and pink or overcast the patch edges. Regardless of the shape of the tear, the patch should be a square, rectangle, or triangle to make sewing it on consistent.
Pin the patch in place and edgestitch it with a straight, short stitch, then topstitch 1/4" from the edgestitching.