[HappyIchigo]

What is most difficult for me is polite language (丁寧語). But of course at the beginning it has been grammar, especially to connect sentences and to find out who or what actually is the subject of a sentence (in case they are not mentioned explicitly). And I also had to get used to get information by context, like to find out yourself whether "くつ" meant 'one shoe', 'two or more shoes' or 'a pair of shoes' in said context.