Oil Refiner’s Founding Family Joins List Of Japan’s Richest As Surging Prices Pump Up Wealth

AsiaEditors' PickOil Refiner’s Founding Family Joins List Of Japan’s Richest As Surging Prices Pump Up WealthByJames Simms, Former Contributor. Jun 08, 2026, 05:47pm EDT--:-- / --:--This voice experience is generated by AI. Learn more.This voice experience is generated by AI. Learn more.This story appears in the June 2026 issue of Forbes Asia. Subscribe to Forbes AsiaMasakazu IdemitsuIdemitsu Kosan Co.,LtdThis story is part of Forbes’ coverage of Japan’s Richest 2026. See the full list here. Amid surging crude prices, the family behind oil refining giant Idemitsu Kosan, represented by board member Masakazu Idemitsu, the grandson of late founder Sazo Idemitsu, is one of five new entries on the list, appearing at No. 47 with a net worth of $1.15 billion. Shares of the company, which reported an over 65% jump in net profit to ¥172 billion ($1.1 billion) for the year ended Mar. 31, rose nearly 50% in the past year. In March the refiner expanded into liquified natural gas, agreeing to pay $500 million for an undisclosed stake in London-based MidOcean Energy, which has LNG projects across Australia, Canada and South America. Two months later, with uncertainty looming over global energy supplies, the company, which had previously set decarbonization goals, announced a medium-term plan to invest ¥1.8 trillion until 2030, over half of it earmarked for its fossil fuels business. Idemitsu Kosan’s roots in petroleum go back to 1913, when its founder started selling fuel for fishing boats. Editorial StandardsReprints & Permissions