Thank you both for your explainations; I thought for a while that kanji was to Japanese what learning Anglo-Saxon is to English- that is, a Quixotic gesture or a non-obligatory challenge. Yet, one has to learn kanji as well as the kanas.
Damn.
By the way, are there many Dutch and Portuguese loan words in Japanese? It's really interesting to see how such languages (of Asian colonists) are adapted to Japanese...