From the time when I was still learning English, I remember that my proficiency took a huge leap forwards when I started playing games and reading books in English. I also know that there are series of "easy reading" books that are specifically designed for people who are in the process of learning English, graded by difficulty so you can pick out the ones that best match your current proficiency.
Is there something like that for Japanese as well? I feel that I've reached the point where I could benefit from playing simple Japanese games and reading simple Japanese books, if there are such things.