Freak_090
Why must we use Desu at the end of each sentence?
The words da and desu are used to predicate sentences, while na and de are particles used within sentences to modify or connect
Japanese sentences with copulae most often equate one thing with another, that is, they are of the form "A is B." Examples:
Watashi wa gakusei da. "I'm a student."
Kore wa pen desu. "This is a pen."
It's also more polite I guess, like how in German they ad 'denn' after requests or commands or end words with an 'e'.
Like:
Was machst du denn? Which I believe is translated as, 'What do you do?' since there's no German word for 'do', it's different.
As to why she says it after EVERY sentence:
Maybe to be cute?
http://www.youtube.com/watch?v=FkVYHUMCCwc&NR=1