Although the base of the Takeda clan, Kai Province included a flat land known as Kofu basin, there were few usable fields available due to the flooding of two major rivers, Kamanashi-gawa River, Fuefuki-gawa River, for which high income from nengu (land tax) was not expected.
武田氏の本拠地である甲斐は平野部である甲府盆地を有するが、釜無川、笛吹川の二大河川の氾濫のため利用可能な耕地が少なく年貢収入に期待ができなかった