Hi Daniel. Thanks for the comment. I wish I could give you a good answer, but I haven’t used the Japanese from Zero 5 book yet. So I don’t know how good it is, or what it teaches. But I do love the other books in the series, so if volume 5 is of the same quality, it would be a good buy. Also, what are your goals? Things I wish I did when I was at an upper intermediate level was to sit down and master all of the essential kanji. Not necessarily writing (which would be awesome though) but reading. I think when you get to a higher level of Japanese, knowing how to read well can really improve your Japanese. You can start to watch Japanese movies/TV shows with Japanese subtitles…that way you get practice reading and have cool material to study. If you can read books, that really helps your Japanese improve as well. Speaking is still #1 though!