I'm Soichiro Tanaka. I would like to express our sincere gratitude to our shareholders and investors for your continued support and advice regarding the business activities of the ENEOS Group. I will now explain the FY 2025 first quarter financial results according to the materials. Please turn to page 3 for financial results highlights. Operating profit for Q1 FY 2025 was JPY 50.3 billion, down JPY 100.5 billion year-on-year, mainly due to the deterioration of inventory valuation resulting from the drop in oil prices. Excluding the impact of inventory valuation, actual operating profit increased by JPY 22 billion year-on-year, driven by higher petroleum product margins and gains from the sale of the maritime transportation business. As for the full-year forecast, we have maintained the forecast announced in May, taking into account uncertainties such as resource prices and exchange rates.
It should be noted that following the partial sale of shares of JX Advanced Metals Corporation and its reclassification as an equity method affiliate, the income of the metals business for the previous fiscal year is presented as "discontinued operations" in the financial statements. In today's presentation, however, to ensure continuity and facilitate year-on-year comparison, we have used the figures announced in August last year, which fully include the income of JX Advanced Metals Corporation. Details are shown on the next slide, so please refer to it later as needed. Please turn to page 6, where we explain our initiatives to improve refinery utilization rates. As shown in the line graph on the left, the Q1 utilization rate, excluding periodic repairs, was below the plan at 74%, mainly due to the occurrence of extremely low probability troubles.
As shown in the bar chart on the right, measures to reduce troubles have steadily delivered improvement. However, we recognize that the occurrence of troubles tends to fluctuate to some extent. In Q1, multiple incidents occurred simultaneously, stemming from legacy design and other factors, leading to a temporary increase in downtime. To prevent the recurrence of troubles, we will ensure rapid and effective horizontal knowledge sharing across the organization. Please turn to page 7. As explained in our fourth mid-term management plan announced in May, we recognize that low-carbon businesses will become increasingly important as transitional energy sources toward carbon neutrality, and we position them as a key area for our efforts. In line with this policy, we are steadily advancing initiatives in various areas such as SAF and LNG.
The content of this slide is a summary of previously issued press releases, so please refer to them later for details. Please turn to page 9. The Dubai crude oil price, shown by the red line, started at $76/barrel at the beginning of the quarter and fell to $69/barrel by the end of the quarter due to the expectations of increased production from eight OPEC+ member countries and concerns over an economic slowdown. The quarterly average was $67, down by $18 year-on-year. As for the exchange rate, yen appreciated against the U.S. dollar, driven by concerns over an economic slowdown stemming from U.S. tariff policies. As a result, the quarterly average was JPY 145 , an appreciation of JPY 11 year-on-year. Please turn to page 10. The Petroleum Products Margin Index was lower than the previous year, affected by a negative time lag.
The Paraziling Margin Index declined year-on-year due to the impact of U.S. tariff policies. Pages 12 and 13 show the overview of Q1 results and operating profit by segment. Let me walk you through the details using the waterfall chart on the following pages. Please turn to page 14. For petroleum products, operating profit excluding inventory valuation was JPY 88.8 billion, an increase of JPY 48.9 billion year-on-year. Although there was a negative time lag impact of JPY 48.4 billion, profit increased due to positive factors such as a JPY 35 billion improvement in margin, expense, and etc., mainly from higher margins excluding time lag effects, and a JPY 63.4 billion improvement in one-time factor from the sale of the maritime transportation business.
For oil and natural gas exploration and production, despite higher volumes from an increased equity interest in Vietnam, operating profit declined by JPY 9.6 billion year-on-year to JPY 13.2 billion, mainly due to lower crude oil and gas prices and the impact of strong yen. Please turn to page 15. For high performance materials, although profitability improved due to increased sales of high performance synthetic rubber for fuel-efficient tires, operating profit declined by JPY 1.3 billion year-on-year to JPY 5.3 billion, mainly due to external factors such as strong yen and lower market prices for butadiene. For electricity, while higher sales volume and full operation of the GOIE thermal power plant contributed to profit growth, operating profit decreased by JPY 1.3 billion year-on-year to JPY 8 billion, mainly due to the loss of one-time profit recorded in the previous fiscal year, which resulted from the review of sales recognition timing following the spin-off.
Please turn to page 16. For renewable energy, although profitability improved due to the startup of new power plants and the reversal of unfavorable weather in FY 2024, operating profit decreased JPY 0.4 billion year-on-year to JPY 0.3 billion, mainly due to upfront expenses for projects under development and impairment losses resulting from tightened regulations. For the other segment, which includes businesses not belonging to any specific segment, operating profit was roughly in line with the previous year, excluding the impact of reduction in equity from the sale of JX Advanced Metals shares. Let me move on to the balance sheet and cash flows on page 17. Cash flow is on the left. Operating cash flow for Q1 was a cash inflow of JPY 182.4 billion, mainly from operating profit excluding inventory valuation of JPY 135.1 billion and depreciation and amortization of JPY 81.1 billion.
Investment cash flow was a cash outflow of JPY 33.4 billion, mainly due to capital investment of JPY 60.5 billion. As a result, free cash flow was a cash inflow of JPY 149 billion, and the net cash flow, including dividend payments and other items, was a cash inflow of JPY 72 billion. As shown in the balance sheet on the right, net interest-bearing debt, including lease liabilities, was JPY 1,816.2 billion, and the net D/E ratio was 0.50 x. This concludes my presentation. Page 18 onwards are for your reference, such as assumptions and sensitivities. Please refer to them later. Thank you for your attention.