In the early Showa period, "Kai shiryo shusei" and "Kai sosho" were published, and the empirical research was initiated by Yamanashi Kyodo Kenkyuukai (Yamanashi Local History Study Group).
昭和初年には『甲斐史料集成』や『甲斐叢書』が刊行され、山梨郷土研究会も発足し実証的研究がスタートした。