diff --git a/SVSim.Bootstrap/Importers/BattlePassMonthlyMissionImporter.cs b/SVSim.Bootstrap/Importers/BattlePassMonthlyMissionImporter.cs
new file mode 100644
index 0000000..9f2bb9d
--- /dev/null
+++ b/SVSim.Bootstrap/Importers/BattlePassMonthlyMissionImporter.cs
@@ -0,0 +1,61 @@
+using Microsoft.EntityFrameworkCore;
+using SVSim.Bootstrap.Models.Seed;
+using SVSim.Database;
+using SVSim.Database.Models;
+
+namespace SVSim.Bootstrap.Importers;
+
+/// <summary>
+/// Idempotent upsert of BP monthly mission rows from <c>seeds/bp-monthly-missions.json</c>.
+/// Keyed by (Year, Month, OrderNum). Rows missing from the seed are LEFT INTACT.
+/// </summary>
+public class BattlePassMonthlyMissionImporter
+{
+    public async Task<int> ImportAsync(SVSimDbContext context, string seedDir)
+    {
+        var seed = SeedLoader.LoadList<BattlePassMonthlyMissionSeed>(
+            Path.Combine(seedDir, "bp-monthly-missions.json"));
+        if (seed.Count == 0)
+        {
+            Console.WriteLine("[BattlePassMonthlyMissionImporter] No seed rows; skipping.");
+            return 0;
+        }
+
+        var existing = await context.BattlePassMonthlyMissions
+            .ToDictionaryAsync(e => (e.Year, e.Month, e.OrderNum));
+        int created = 0, updated = 0;
+        var unmapped = new List<string>();
+        foreach (var s in seed)
+        {
+            if (s.Year == 0 || s.Month == 0) continue;
+            var key = (s.Year, s.Month, s.OrderNum);
+            var entry = existing.TryGetValue(key, out var ex)
+                ? ex
+                : new BattlePassMonthlyMissionEntry
+                {
+                    Year = s.Year, Month = s.Month, OrderNum = s.OrderNum,
+                };
+            entry.Name = s.Name;
+            entry.RequireNumber = s.RequireNumber;
+            entry.BattlePassPoint = s.BattlePassPoint;
+            entry.RewardType = s.RewardType;
+            entry.RewardDetailId = s.RewardDetailId;
+            entry.RewardNumber = s.RewardNumber;
+            entry.EventType = s.EventType;
+            entry.EventArg = s.EventArg;
+            if (ex is null) { context.BattlePassMonthlyMissions.Add(entry); existing[key] = entry; created++; }
+            else updated++;
+            if (s.EventType is null) unmapped.Add($"{s.Year}-{s.Month:00}/{s.OrderNum}");
+        }
+
+        await context.SaveChangesAsync();
+        Console.WriteLine($"[BattlePassMonthlyMissionImporter] +{created}/~{updated}");
+        if (unmapped.Count > 0)
+        {
+            Console.WriteLine($"[BattlePassMonthlyMissionImporter] WARN: {unmapped.Count} rows " +
+                              $"with no event_type: [{string.Join(", ", unmapped)}] — add name to " +
+                              "BP_MONTHLY_EVENT_MAP in data_dumps/extract/extract-bp-monthly-missions.py");
+        }
+        return created + updated;
+    }
+}
diff --git a/SVSim.Bootstrap/Models/Seed/BattlePassMonthlyMissionSeed.cs b/SVSim.Bootstrap/Models/Seed/BattlePassMonthlyMissionSeed.cs
new file mode 100644
index 0000000..a7555ff
--- /dev/null
+++ b/SVSim.Bootstrap/Models/Seed/BattlePassMonthlyMissionSeed.cs
@@ -0,0 +1,18 @@
+using System.Text.Json.Serialization;
+
+namespace SVSim.Bootstrap.Models.Seed;
+
+public sealed class BattlePassMonthlyMissionSeed
+{
+    [JsonPropertyName("year")] public int Year { get; set; }
+    [JsonPropertyName("month")] public int Month { get; set; }
+    [JsonPropertyName("order_num")] public int OrderNum { get; set; }
+    [JsonPropertyName("name")] public string Name { get; set; } = "";
+    [JsonPropertyName("require_number")] public int RequireNumber { get; set; }
+    [JsonPropertyName("battle_pass_point")] public int BattlePassPoint { get; set; }
+    [JsonPropertyName("reward_type")] public int? RewardType { get; set; }
+    [JsonPropertyName("reward_detail_id")] public long? RewardDetailId { get; set; }
+    [JsonPropertyName("reward_number")] public int? RewardNumber { get; set; }
+    [JsonPropertyName("event_type")] public string? EventType { get; set; }
+    [JsonPropertyName("event_arg")] public int? EventArg { get; set; }
+}
diff --git a/SVSim.UnitTests/Importers/BattlePassMonthlyMissionImporterTests.cs b/SVSim.UnitTests/Importers/BattlePassMonthlyMissionImporterTests.cs
new file mode 100644
index 0000000..9db4522
--- /dev/null
+++ b/SVSim.UnitTests/Importers/BattlePassMonthlyMissionImporterTests.cs
@@ -0,0 +1,86 @@
+using Microsoft.EntityFrameworkCore;
+using Microsoft.Extensions.DependencyInjection;
+using SVSim.Bootstrap.Importers;
+using SVSim.Database;
+using SVSim.UnitTests.Infrastructure;
+
+namespace SVSim.UnitTests.Importers;
+
+public class BattlePassMonthlyMissionImporterTests
+{
+    private static string SeedDir => Path.Combine(AppContext.BaseDirectory, "Data", "seeds");
+
+    [Test]
+    public async Task Imports_may_2026_captured_rows()
+    {
+        using var factory = new SVSimTestFactory();
+        using var scope = factory.Services.CreateScope();
+        var db = scope.ServiceProvider.GetRequiredService<SVSimDbContext>();
+
+        await new BattlePassMonthlyMissionImporter().ImportAsync(db, SeedDir);
+
+        int mayCount = await db.BattlePassMonthlyMissions.CountAsync(r => r.Year == 2026 && r.Month == 5);
+        Assert.That(mayCount, Is.EqualTo(5), "May 2026 captured 5 monthly mission rows");
+
+        var noRewardRow = await db.BattlePassMonthlyMissions
+            .SingleAsync(r => r.Name.StartsWith("Play 5 Challenge"));
+        Assert.That(noRewardRow.RewardType, Is.Null, "Play 5 Challenge has no reward_info on wire");
+    }
+
+    [Test]
+    public async Task Multiple_months_coexist()
+    {
+        using var factory = new SVSimTestFactory();
+        using var scope = factory.Services.CreateScope();
+        var db = scope.ServiceProvider.GetRequiredService<SVSimDbContext>();
+
+        db.BattlePassMonthlyMissions.Add(new SVSim.Database.Models.BattlePassMonthlyMissionEntry
+        {
+            Year = 2026, Month = 6, OrderNum = 0,
+            Name = "future placeholder", RequireNumber = 1, BattlePassPoint = 100,
+            EventType = "ranked_or_arena_win",
+        });
+        await db.SaveChangesAsync();
+
+        await new BattlePassMonthlyMissionImporter().ImportAsync(db, SeedDir);
+
+        int mayCount = await db.BattlePassMonthlyMissions.CountAsync(r => r.Year == 2026 && r.Month == 5);
+        int juneCount = await db.BattlePassMonthlyMissions.CountAsync(r => r.Year == 2026 && r.Month == 6);
+        Assert.That(mayCount, Is.EqualTo(5));
+        Assert.That(juneCount, Is.EqualTo(1));
+    }
+
+    [Test]
+    public async Task Is_idempotent_on_rerun()
+    {
+        using var factory = new SVSimTestFactory();
+        using var scope = factory.Services.CreateScope();
+        var db = scope.ServiceProvider.GetRequiredService<SVSimDbContext>();
+
+        await new BattlePassMonthlyMissionImporter().ImportAsync(db, SeedDir);
+        int before = await db.BattlePassMonthlyMissions.CountAsync();
+        await new BattlePassMonthlyMissionImporter().ImportAsync(db, SeedDir);
+        int after = await db.BattlePassMonthlyMissions.CountAsync();
+
+        Assert.That(after, Is.EqualTo(before));
+    }
+
+    [Test]
+    public async Task Empty_seed_is_no_op()
+    {
+        using var factory = new SVSimTestFactory();
+        using var scope = factory.Services.CreateScope();
+        var db = scope.ServiceProvider.GetRequiredService<SVSimDbContext>();
+
+        string tmp = Path.Combine(Path.GetTempPath(), $"seed-{Guid.NewGuid()}");
+        Directory.CreateDirectory(tmp);
+        try
+        {
+            File.WriteAllText(Path.Combine(tmp, "bp-monthly-missions.json"), "[]");
+            await new BattlePassMonthlyMissionImporter().ImportAsync(db, tmp);
+            int count = await db.BattlePassMonthlyMissions.CountAsync();
+            Assert.That(count, Is.EqualTo(0));
+        }
+        finally { Directory.Delete(tmp, true); }
+    }
+}