We expect "satoshi nakamoto" is japenese.
When you take out "I am Nash" you are left with
"sato" and "koto"
Japenese is the key because if you didn't know the language then you could never match the words to verify the code cracking
sato = the most popular japenese name
koto = japan's national instrument
Off topic, but this reminded me of Dan Brown's book on Cryptography/Code breaking: Digital Fortress, 1998
Fletcher discovers through a tracer that North Dakota and Ensei Tankado are actually the same person, as "NDAKOTA" is an anagram of "Tankado".