Upon attending the opening ceremony of a museum in April in Tottori Prefecture, veteran Liberal Democratic Party lawmaker Shigeru Ishiba made a sidesplitting appearance by dressing up as Majin Boo — the pudgy, baby-like villain in the popular anime "Dragon Ball."

Funny as it was, his imitation of Majin Boo, the ultimate antagonist in the show, was apt in one sense: Ishiba is now on course to become one of Prime Minister Shinzo Abe's biggest adversaries in the LDP's presidential election slated to kick off in September.

Famous for his extensive military knowledge, which has earned him the title gunji otaku (military geek), Ishiba, 61, has held multiple portfolios from agriculture to defense.