Yes it does make a difference because the wealthy individuals who own many units can drive up the price by restricting supply. They can influence zoning laws and block new high-density construction to protect their profits.

That still doesn't make sense. If you have no one living in an investment unit you're losing money. Could an owner of manu units increase pricing by not renting/selling at market rates? Sure but they'd be losing money.

And yet it happens all the time. There are many units in my city in very desirable locations that have been empty for a long time. Often they do temporarily allow people to live there ('anti-squat'), but they can be kicked out at a month's notice and have basically no rights.

What makes this so frustrating is that anyone moving to the city has to either pay exorbitant amounts of money for tiny apartments or rooms, or live far out of the center.

I'm not Seiji, but I think he wants to make illegal for both investment companies and private individual to own more than a certain number of apartments, in order to prevent real estate price to go up and up, to which I wholeheartedly agree.