The secret of ultra-thin, ultra-thin single-faced file thin-bladed rice ball (Usuba Onigiri) sharpness is at the cutting edge with an edge like a single blade. 
The orderly and neatly arranged files ensure sharp and smooth cut skin.

Ultra-thin, 1-mm thick, 4-mm wide, ultra-thin single file. 

Both sides can be used.

I asked for the beauty of the cut skin by a single eye. 

It is hard to get clogged, and even if it looks clogged it can be easily removed by brushing it.