These varieties of koi are the yin and yang of scaled and Doitsu blue koi. Asagi have blue, net-like reticulated pattern across the back. They will have areas of red (hi) on the gill plates, pectoral fins, belly, tail, and possibly around the dorsal fin.
Shusui are Doitsu (German) koi where the blue scaleless skin replaces the Asagi’s scaled net pattern. They have a single row of scales running down the back (dorsal line). The Shusui will also exhibit red (hi) in similar spots, but it can extend above the lateral line and onto the back.