2.23.7 is very good time. The record of Turkish the most famous derby Gazi Kosusu is made by Bold Pilot and it's around 2.26 and it couldn't break since for 1996.
Considering how difficult a lot of these Japanese horses are to beat on racetracks in Japan, and given what a very difficult post position he had to overcome breaking from stall #14 of 17, I thought Idaho ran a very creditable race here in the Japan Cup to finish 5th of 17, IMO.