Japanese is very difficult for English native speakers to learn. One reason that Japanese is so difficult to learn is that the kanji character system that the language uses is completely unrelated to the Western alphabet.
Japanese requires several thousand hours of studying in order to gain proficiency. The more similar a language is to one's native tongue, the easier it is for that person to learn it. Japanese is completely unrelated to English.
Japanese utilizes three character systems: kanji, katakana and hirigana. Because a paragraph in Japanese might employ all three writing systems, students must learn all three, not just a single system.