[Carfanate]

As a very minimum, you must be able to read hiragana and katakana. In the beginning people like to learn the language in romanji because it is easier to them and it is fast... at first. But learning to read hiragana and katakana doesn't take that much time and once you get past the initial difficulty, it is simple and will give you more flexibility. So don't be lazy and at least learn to read that. Kanji may not be so important, but people who refuse to study in anything but romanji can stunt their growth so don't be tempted.