Idemitsu Kosan : Announcement on Differences between Forecast and Actual Performance

Press Release

May 12, 2026

Company Name: Idemitsu Kosan Co.,Ltd. Representative Director and President: Noriaki Sakai (Company Code: 5019, TSE Prime Market)

Contact person: Shinko Sasaki, General Manager, Investor Relations Office, Finance Department

Telephone: +81-3-3213-9307

Idemitsu Kosan Co., Ltd. (hereinafter, "Idemitsu") hereby announces differences between forecast for the fiscal year ended March 2025 (April 1, 2025-March 31, 2026) announced on November 11, 2025 and actual results announced today, as follows.

1. Differences between the Consolidated Financial Results and Forecasts in the Fiscal Year Ended March 2025 (April 1, 2025-March 31, 2026)

   (Units: JPY millions, JPY)

   	Net Sales (JPY millions)	Operating Income (JPY millions)	Ordinary Income (JPY millions)	Net Income Attributable to Owners of the Parent (JPY millions)	Net Income per Share (JPY)
   Previous Forecast (A)	7,950,000	68,000	85,000	75,000	61.24
   Actual Result (B)	8,105,891	212,203	229,646	171,914	140.38
   Difference (B - A)	155,891	144,203	144,646	96,914
   Change (%)	2.0%	212.1%	170.2%	129.2%
   (Reference) Previous FY R e s u l t s ( F Y 3 / 2 0 2 5 )	9,190,225	162,185	214,764	104,055	77.83

2. Background for Differences between Forecast and Actual Performance in the Fiscal Year Ended March 2026

Operating income increased by 144.2 JPY billion and Net Income Attributable to Owners of the Parent increased by 96.9 JPY billion JPY mainly due to an expansion of the positive time-lag impact in the petroleum segment resulting from an increase in crude oil price.

（Assumptions） （Units: USD/bbl, JPY/USD）