I had several Japanese teachers in the past (both at Jap school and private) and Yumiko is by far the best one. Explanation is very clear and the best thing is that she speaks perfect English (she lived many years in the US). That's very useful because when things get too complex to understand in Japanese you can switch to English explanation and you can even compare very complex grammar forms directly to English. So for me things that in the past were inexplicable, become clear in 5 seconds. After I started classes with her, my Japanese started increasing right away. Highly recommended.