Far backcountry life in Japan

I originally thought 4 seasons are quarterly divided like 3 month spring, 3 month summer and so on. In Tokyo and Yokohama where I grown up, I really feel like so but in Nakagawa-machi, I feel spring and autumn are 1 month each and other 10 months are summer and winter. Spring and autumn are passing so quickly. Spring is around May and autumn is mid September to mid October. This 2-month is best visit.