Japan's ruling and opposition parties have decided to summon Yasunori Kagoike, head of the Osaka-based education institution Moritomo Gakuen, to Diet, or Japan's parliament to answer questions on March 23.

Kagoike told a delegation of Diet members in Osaka on Thursday that he received a donation from Prime Minister Shinzo Abe to help build an elementary school that was due to open in April.

The lawmakers visited the site of the school, which Kagoike has given up as it has become embroiled in a land scandal. Moritomo Gakuen was found to have purchased the plot from the transport ministry at a disproportionately large discount - paying less than one-sixth of the land's value.

Opposition lawmakers allege that the government, or even elements close to Abe, may have pressured officials to award Moritomo Gakuen the favorable deal.

Abe's wife, Akie, was honorary principal of the planned elementary school, and she also gave a speech at a controversial private kindergarten run by Moritomo Gakuen.

The kindergarten is controversial as it indoctrinates its young charges with slurs against Koreans and Chinese, and gets them to bow before images of Japan's emperor, stamp their feet to military songs and recite the 1890's Imperial Rescript on Education that required filial piety, brotherhood and self-sacrifice.

Abe has tried to distance himself from Kagoike. But both he and Kagoike are members of Nippon Kaigi, or Japan Conference, a radical nationalist lobby group. Abe serves as its "special adviser", and Kagoike heads its Osaka branch.

Nippon Kaigi, is a small group, with about 38,000 fee-paying members. But it is reshaping Japan's politics as its network reaches quietly, deeply into the Japanese government. Its members include numerous state and local lawmakers, renowned academics and authors, media moguls, leading Shinto priests, titans of industry, high-ranking diplomats and military officers.

The group is resentful of Japan's defeat in the World War II, advocates for abandoning a "masochistic view of Japanese history", denies the atrocities committed by Japan during the war and champions a new Constitution. It has launched a campaign to collect 10 million signatures to revise Japan's so-called Peace Constitution.

Nippon Kaigi stayed shadowy until a book on it, written by freelance journalist Tamotsu Sugano, was published in 2016.

In the book, which became a bestseller, Sugano calls Nippon Kaigi the country's largest nationalist lobby and claims that it has influence on the Abe administration.

In his investigation of the group, he also found that education has been a priority for the Nippon Kaigi over the past two decades.

Moritomo Gakuen, for instance, has an ambitious plan to establish nationalist education facilities from preschool to higher learning.

Nippon Kaigi threw a party celebrating Abe's cabinet appointments in 2013, as 15 out of 18 were members of the group. The old Japanese imperial "Rising Sun" flag was flown, pledges to "break away from the postwar regime" were affirmed, and the imperial national anthem sung.

"Go, go Prime Minister Abe! We're happy you passed security legislation at the Diet!" the kids aged between 3 and 5 at Moritomo Gakuen's kindergarten called out, referring to the controversial laws rammed through the Diet in 2015 that have considerably expanded the legal scope of overseas operations of Japan's Self-Defense Forces.

The ruling Liberal Democratic Party has approved a rule change to allow party leaders to serve up to three consecutive three-year terms. The move allows Abe to potentially stretch his tenure through 2021.

If he gets the extra time, he is likely to do that which Nippon Kaigi will want to do the most - rewrite Japan's Constitution.

The author is China Daily Tokyo bureau chief. caihong@chinadaily.com.cn