Several years back I lived in Tokyo for a couple of years. I like learning the local language. I could mostly get by with the spoken Japanese (Nihongo). Tried to learn the script but failed miserably. It's a combination of Hirgana alphabets, Katakana alphabets and to top it all 10s of thousands of Chinese Kanji. Loved my stay, very polite people. I think their vocabulary doesn't have the word impolite (polite and less polite). I would say Japanese script is one of the hardest if not hardest.