The story is like this. Amigo (he's a monkey, and "Amigo" is his birth name.) had a poor family. "How poor?" you may ask. To the point where Amigo's clothes were rags. That's how poor he is. But one fateful day, Amigo was in the town plaza, and looked inside a music shop window and saw the very objects that will change his life forever. 2 bright red maracas, trimmed with a green and yellow zig-zag ring. Amigo asked the shopkeeper to give him the maracas (which he did), became a fabulous musician using those 2 maracas, and became famous. In fact, he was known as the Maracas King (either that or the Music King). After preforming songs everywhere, he went back home (he's still a kid at heart), where his sister would change Amigo's life forever (again). His sister (Amiga) asked Amigo to form a duet with her. She would do the dancing, and Amigo would do the music. Now they perform together as a musical duet. And that's the story of Samba De Amigo.
The gameplay is easy to understand but hard to master. When you see dots heading for the Red circles, shake the Wii Remote and Nunchuck up high. When you see dots heading for the Yellow circles, shake the Wii Remote and Nunchuck in the middle. When you see dots heading for the Green circles, shake the Wii Remote and Nunchuck down low.
NOTE: Image from Wikipedia.