How does TAkeshi Finger Spin?

How does he finger spin with the isotope 2?
Theres that thing coming out from the middle, so does he grind in the circle gap around it?
Also, is his orange isotope 2 blasted?

Yes, he grind on that circle around it. You dont need completly flat side to get decent finger grinds, with enough practice, you can finger grind on almost all yo-yos.