I think they were Toyo DRB's. Can't vouch for them personally, but my cousin who is suffering from withdrawal from his big bike days only uses DRB's or Yoko S.drives. Too bad S.drive is out of stock.
Potenzas are really expensive. But they do have MY02 which should be cheaper. Sidewall seems soft for a "sporty" tire.
For the Taiwanese brands I only know Nankang NS2-r, but these are semi slicks only for dry track use. My friend's sponsored drifting team uses them.
I don't blame you for considering Japanese brands bro. They make some good tires.

the Toyos should be cheaper than BS or Yoko. Dunlop I avoid like the plague, sidewalls are really soft and tread gets too many punctures.