Coming from, China, a poor country then compared to Japan, he and his brother were forced to go to Japan to seek for better education, which will eventually lead to a better life. There is so much feeling of anxiousness in his heart. The narrator seems to look at things, always on the negative side. He never seeks for contentment.
As he walks back going to his home he begins to feel calm. There seems to be a change of heart, because of the beautiful weather, he vividly described the beauty of the plants and the flowers which seemed to have touched his heart. Indeed, the beauty of Japan is undeniable, that no matter how uncomfortable you are right now, or how unwelcome you think you are, the beauty of the Japanese scenery will even for a while, change your heart and mind.
In my opinion, the narrator experiences the terrible sense of home sickness. And the simplicity of his home, compared to the somewhat faster paced Japanese setting makes him feel out of touch. Maybe it is a normal feeling, being so young and being away from home, and imagining the expectations of family members back home, it is sometimes uncontrollable to be hard on oneself.
According to the narrator, when all else fails, you can conveniently go back to nature, be in its bosom. And I think this applies to all cultures. ...