maybe next time, slice his head in half then we will see if he can heal himself still.
and you have to give it to him, he actually stay calm even with his arm cut off, he either feel nothing or already used to pain enough to do so.
Thanks for the upload, so Yamada has that Timberwolves Ant/pimp grindset. So to beat Yamada there's primarily 4 ways they can beat him. 1. Oneshot him or take out his head/brain and see if that will impact his ability to heal or negate it. 2. See if they can overwhelm or burn out his healing ability. 3.Try to use his skill against him 4. Inflict something on him so horrific/gruesome that he won't want to heal it or keep enduring it so he would rather die then keep going through it. So trapping him in some form of very painful, healing cycle/loop.
The only other way I can see him dying would be to nullify his ability but considering their fight with the previous reincarnate I think we can believe that she doesn't have that type of ability.