Some Japanese learners have a tendency to want to discuss the logic and reasoning behind some corrections, and are very interested in studying grammar. This tendency gets complicated. This kind of learning also becomes learning about English, not learning English. Learning, understanding, and remembering complicated rules with many exceptions is too difficult. Students would often do far better to read more, exposing themselves to more and more writing. Students improve writing through getting a feeling for English. Your getting a feeling comes from your writing practice, seeing your writing corrected, and your reading. Reading is essential.