diff --git a/SVSim.Bootstrap/Importers/BattlePassSeasonImporter.cs b/SVSim.Bootstrap/Importers/BattlePassSeasonImporter.cs
index 0f8b9bc..6383949 100644
--- a/SVSim.Bootstrap/Importers/BattlePassSeasonImporter.cs
+++ b/SVSim.Bootstrap/Importers/BattlePassSeasonImporter.cs
@@ -29,8 +29,11 @@ public class BattlePassSeasonImporter
             var entry = existing.TryGetValue(s.Id, out var ex) ? ex : new BattlePassSeasonEntry { Id = s.Id };
             entry.Name = s.Name;
             entry.MaxLevel = s.MaxLevel;
-            entry.StartDate = DateTimeOffset.Parse(s.StartDate, CultureInfo.InvariantCulture, DateTimeStyles.AssumeUniversal);
-            entry.EndDate = DateTimeOffset.Parse(s.EndDate, CultureInfo.InvariantCulture, DateTimeStyles.AssumeUniversal);
+            // Postgres 'timestamp with time zone' only accepts UTC offset; JST-offset values
+            // from the seed are converted to UTC to preserve the instant. Comparisons via
+            // DateTimeOffset are instant-based, so the JST→UTC conversion is semantically lossless.
+            entry.StartDate = DateTimeOffset.Parse(s.StartDate, CultureInfo.InvariantCulture, DateTimeStyles.AssumeUniversal).ToUniversalTime();
+            entry.EndDate = DateTimeOffset.Parse(s.EndDate, CultureInfo.InvariantCulture, DateTimeStyles.AssumeUniversal).ToUniversalTime();
             entry.CanPurchase = s.CanPurchase;
             entry.PriceCrystal = s.PriceCrystal;
             entry.Description = s.Description;
diff --git a/SVSim.UnitTests/Importers/BattlePassSeasonImporterTests.cs b/SVSim.UnitTests/Importers/BattlePassSeasonImporterTests.cs
index 0ab0f19..9489134 100644
--- a/SVSim.UnitTests/Importers/BattlePassSeasonImporterTests.cs
+++ b/SVSim.UnitTests/Importers/BattlePassSeasonImporterTests.cs
@@ -24,8 +24,10 @@ public class BattlePassSeasonImporterTests
         Assert.That(season.MaxLevel, Is.EqualTo(100));
         Assert.That(season.CanPurchase, Is.True);
         Assert.That(season.PriceCrystal, Is.EqualTo(980));
-        Assert.That(season.StartDate.Offset, Is.EqualTo(TimeSpan.FromHours(9)),
-            "JST offset (+09:00) must round-trip through DateTimeOffset");
+        // JST-offset seed is converted to UTC for Postgres 'timestamp with time zone' compatibility.
+        // Semantically lossless — the instant 2026-04-01T02:00+09:00 == 2026-03-31T17:00 UTC.
+        Assert.That(season.StartDate.Offset, Is.EqualTo(TimeSpan.Zero));
+        Assert.That(season.StartDate.UtcDateTime, Is.EqualTo(new DateTime(2026, 3, 31, 17, 0, 0, DateTimeKind.Utc)));
     }
 
     [Test]