You're right, this situation would have been swiftly reversed by VAR had it been in play. But situations like this when something this blatant is missed are incredibly rare. I mean, this is Henry handball territory.
What I would say is that something like this, which might happen once in a blue moon, does not justify the monstrosity that VAR is that causes all kinds of problems in other areas.
I could live with an occasional howler like this if it meant that we had free flowing football. I would also say that if VAR was only limited to catching clear "intentional" handballs like this that were missed in real-time, that led to goals, I could probably live with it.
It's all the other nonsense that VAR looks at which isn't "clear or obvious". For example, evaluating fouls or tackles with VAR, or for seeing the ball hit off a hand inadvertently then using that to rule out goals, when it wasn't intentional, that's very different and that's what drives people up a wall about VAR.
So I agree with you here, VAR would be very effective and catching something blatant like this Yu Hirakawa handball. And it would only need to be looked at if it led to a goal. If this didn't lead to a goal, then play on. No stoppage needed.