How does Yoshimitsu's health drain grab work?

One of Yoshimitsu's grabs is a health drain, where he grabs an opponent by the head and drains their HP. Sometimes, however, the exchange goes the opposite way, with Yoshimitsu losing HP and the opponent gaining it. At first I thought it may have had to do with which player had more HP, or Yoshimitsu position to the enemy, but neither of these seem to be the case (but I could easily be wrong, since testing this mid battle is very difficult). At this point I'm starting to think it's just completely random, which is certainly possible, but it's always trick to determine when something is random.

How does Yoshimitsu's health drain grab attack work, and what determines whether HP is gained or lost?

Solution 1:

If the oponent manages to tech the grab, yoshimitsu still performs it, but looses health in the process. It's not something random