Jump on the bottom of the upper most ectoplasm cloud on Crossing so that you are standing upside down. Approach the left most edge. Hold up, & execute the super jump while navigating towards the left hole on the bottom of the screen. To properly execute, it is integral you continue to hold up, jump & slash until the full circle is completed.

There are a few places you can kill opponents while sheathing after doing this, primarily the vertical two block island above the bottom right screen warp, & if timed right the block immediately beneath the top right spawn point.
It's also a fun way to engage in combat in general. Once you reach the highest point of momentum after coming up out of the right screen warp you can also down slash & fling yourself back in through the warp & up on to the other side of the screen again.

Have fun feeling awesome if you can pull this off.