Some background on sake lees vinegar (aged) / akazu, although I got it a little wrong in Feb 2017… akazu is more aromatic and a bit more sweet on the nose and taste than rice vinegar (which gives the rice more punch and sour, accentuated more with salt, but akazu needs salt to draw more nuance out…although some places add sugar).
Shunji and SGO use the exact same brand/bottle of akazu.