JEPX day-ahead clearing for 12 November: the system average printed ¥29.82/kWh, down ¥0.61 day-on-day, but the intraday shape is far more extreme than the average suggests — a ¥41.99 evening peak at 17:00 against a ¥8.17 trough at noon, a 5.1x peak-to-trough ratio. JEPX Pulse puts the system-level solar midday depression at 84% (¥11.38 midday average versus ¥29.82 for the full day). Kyushu posted the lowest area average at ¥20.92 with 1.5 hours of ¥0.01 floor prices, and floor-price hours across all areas have totaled 45 over the past seven days.

Regional dispersion is equally stark: Tokyo led the country at ¥34.26/kWh, ¥13.3 above Kyushu — a relative east-west gap above 60%. The low-price region pays for it in curtailment: Kyushu curtailed 6,162 MWh of renewables on the day, roughly half a day's output from a mid-sized nuclear unit. The higher the solar penetration (Kyushu, Shikoku, Chugoku), the deeper the midday collapse, while evening peaks converged at ¥41.8–42.0 across all nine areas — evidence that the marginal price-setting unit in the 17:00–20:00 window is, almost nationwide, gas- and oil-fired ramping capacity.

The duck curve carries a dual message for Japan's energy system. Midday hours are being systematically occupied by solar, compressing gas-plant operating hours into morning and evening blocks and shifting fleet economics from baseload to two-shift ramping, with higher start-stop and low-load costs per MWh. At the same time, the ¥42 evening peak signals that gas-fired flexibility still locks in substantial revenue between 17:00 and 20:00, so spot LNG procurement will increasingly be planned around evening-peak exposure rather than around-the-clock baseload. In volume terms solar substitutes for LNG; in time-structure terms it reinforces gas's marginal pricing role.

Implications for SNSUC. First, Japanese utilities' spot LNG demand elasticity will concentrate in cold-snap-plus-evening-peak scenarios — inquiry windows may become shorter and more urgent, making response speed and schedule certainty the core of competitiveness. Second, east-west price dispersion creates arbitrage room for inter-regional transmission and storage business models, and rising Japanese customer willingness to invest in power infrastructure is worth tracking as a medium-term demand signal. Third, our accessible slate spans LNG/LPG, base oils SN150/SN500, paraffin wax and lubricants; hazardous chemicals remain strictly excluded, and all Japan-facing business stays within this perimeter. Risk note: this is a market observation based on public data and does not constitute investment advice.