Moritomo Gakuen, the nationalist school operator at the center of a political scandal over its bargain-price purchase of state land, was sued Wednesday for alleged unpaid construction costs related to a newly built elementary school at the site.

Fujiwara Kogyo, an Osaka-based construction company, filed a lawsuit with the Osaka District Court demanding Moritomo Gakuen pay about ¥400 million that was due on March 31. The total unpaid amount exceeds ¥1.6 billion, the firm said.

Moritomo Gakuen bought the 8,770-sq.-meter plot of land for the school in the city of Toyonaka, Osaka Prefecture, last June at more than ¥800 million below its appraised value.