Stir water and sugar together in a small saucepan over high heat. Bring to a boil and add walnuts. Boil for 2 minutes, then drain and place walnuts on a cookie sheet to dry.

Whip egg whites in a medium bowl until foamy. Stir in mochiko until it has a pasty consistency.

Heat oil in a heavy deep skillet over medium-high heat. Dip shrimp in mochiko batter, then fry in batches in hot oil until golden brown, about 5 minutes.

Remove with a slotted spoon and drain on paper towels.

Stir together mayonnaise, honey, and sweetened condensed milk in a medium serving bowl.