The above video shows someone using Jago and I will be doing a breakdown of what is going on in the video below.
Get a friend (that would be preferable but you can do this on a random player that joins too) in a Exhibition match with you and then beat them up and get rid of their first bar and then beat them up some more till they're at red low health and make sure you have full shadow meter on the bottom of your side of the stats screen, then have them beat you up till you have full instinct meter which is the bar below your health and it should glow to let you know it's full.
1. Start doing a combo and use both shadow meters and rack up a bit over 20 hits or until the bar is almost filled
2. Use ultra
3. After about 40 hits or so, do a instinct cancel
4. Continue doing your combo, use your two shadow meters again and you should be in the 60 hits range
5. Use your ultra again
6. You should be a few hits off now so after the punch from the ultra that launches them in the air do whatever shadow moves you want when they come back down to push you to 100 or over hits
It should unlock as soon as the stats screen pops up.
Practice doing this in training mode if you're unsure if you can pull it off. You can set the CPU to 'danger' health so you can try it quickly over and over again.
I don't know if there's a easier character to do this with but I figure most everyone knows how to play with Jago to some degree and it isn't all that complicated, this can be done with other characters though you just need to know when to cancel during that characters ultra but use whoever you're most comfortable with.