For pure residential, ranging 0.5-2mio USD, I’m seeing something like 5-8% outside of central Tokyo vs 2-5% in central Tokyo. 

Congrats - house hack or pure rental?

I was told that they can do it as low as 5.75% for 12 mos, no docs just purely asset base, no prepayment penalty.I am new to this.

So someone who is looking purely to maximize potential return (and has unlimited time) is unlikely to find this a good fit. 

Quote from @Anderson Banegas Cerrato: Elijah, this is pure fire, man!

I have financed a number of STR properties and they will usually be appraised as a pure real estate as vacant value and a cash flow adjusted commercial value, sometime separated as going concern and real property.  

In hindsight I can see all the mistakes I made but...pura vida.I do my proformas and try to calculate returns but I don't measure the value of investments purely on these terms like some others who've responded to you.

If so, and you're looking at a purely rental property (not to live in at any point) you could consider opening a self-directed IRA to invest in the new property without having to pull money out and pay penalties?

Stock picking is gambling pure and simple. 

The “moderate size” question is pure opinion.