The Otamatone is a synthesizer with a body shaped like a musical note.
It also somewhat resembles a tadpole, which in Japanese is called otamajakushi.
Playing it requires two hands: while one hand holds and squeezes the "head," the other hand controls the melody by placing a finger on the stem.
The controller is logarithmic to resemble a string instrument, so there is less distance between higher notes than between lower ones.
Changing the pressure on the head (thus opening and closing the "mouth" of the Otamatone) creates a wah-wah effect, and shaking the neck (and thus slightly varying the pressure on the head) creates a vibrato effect.
The switches on the back of the head allow users to change the octave, turn it off or on, or change the volume.