Though Mori has some anecdotes that can appeal to pathos, most of the essay is based on logos as she describes the differences between the American school system and the Japanese one. She bases her argument on the structural differences between the two.
She addresses the fact that teachers in Japan generally feel no responsibility to help a student whereas teachers in the united States tend to feel that they ought to help students when they struggle. She notes the lack of schools or groups where one could learn to write creatively in Japan while there were all kinds of groups that she was able to join in the United States.
So she is trying to show that the Japanese system is not necessarily one to be followed and her argument is based almost entirely on logos.
Well, let us look at the difference between logos and pathos in order to determine why kapokkid's answer is correct. In short, (and according to their roots) logos has to do with words and pathos has to do with emotions. Thus, logos has a focus on the logical presentation and explanation of simple facts in order to persuade while pathos has a focus on emotional ideas through images in order to persuade.
Mori spends most of her time describing the (exact) differences between the American school system and the Japanese school system; therefore, these rational facts appeal to logos. In fact, her argument is specifically about the differences in structure between about the two school systems. Some specifics, in regards to logos, that Mori relates are about teacher responsibility. In the American school system, teachers feel responsible for helping a struggling student. In the Japanese school system, teachers do not feel responsible (at all) for helping a student who is struggling. Mori also relates the differences in regards to creative writing. In the Japanese school system, students are encouraged to write "correctly" and not necessarily creatively. In the American school system, students are encouraged to both write correctly and creatively.
In conclusion, the previous answer is completely correct to say that the author concentrates solely on logos here: the presentation of rational facts. What I find ironic is that Mori feels more at home in the American school system (because her creative writing is encouraged); however, she writes based on logos (the expression of rational facts).