Nakamoto is a bit long, I will admit, but it is only 1 syllable more than satoshi.
Naka could work as well. This would just be 中. This is also the short country name of China (中国). 中 could be the currency symbol. It is already in unicode...

新 means "new" and is pronounced the same in Chinese and Japanese (xin/shin). That character is also in unicode!!