About lyric poetry, Wordsworth said that it was "the spontaneous overflow of powerful feelings." He implied that something repressed builds and breaks, and that the faster the flow, the fuller the stress.
If this is true, then it is not surprising there are so many Japanese women poets. Merely being a woman in Japan can be, depending upon the circumstances, a stressful situation.
Until recently regarded as chattel — the personal possession of some man — denied many a male prerogative, and otherwise seen as fodder fit for becoming only a good wife and a wise mother, the Japanese woman has traditionally had a lot to put up with.