江戸三作 Edo Sansaku

What is Edo Sansaku in Japanese Katana terminology?

"Edo Sansaku" refers to the three swordsmiths among the Shinshinto blacksmiths who were based in Edo and possessed excellent skills. These include "Suishinshi Masahide", "Taikei Naotane", and "Minamoto no Kiyomaro".