*Yen Drops To Near 3-week Low Of 170.55 Against Swiss Franc

*Yen Edges Down To 161.01 Against Euro

*Yen Slides To 3-week Low Of 90.74 Against NZ Dollar

*Yen Falls To 3-week Low Of 193.28 Against Pound

*Yen Slides To Near 3-week Low Of 144.68 Against U.S. Dollar