diff --git a/src/main/scala/com/github/unchama/seichiassist/util/BreakUtil.scala b/src/main/scala/com/github/unchama/seichiassist/util/BreakUtil.scala
index d1decbd78a..bfeae97e63 100644
--- a/src/main/scala/com/github/unchama/seichiassist/util/BreakUtil.scala
+++ b/src/main/scala/com/github/unchama/seichiassist/util/BreakUtil.scala
@@ -20,6 +20,7 @@ import org.bukkit.entity.{Entity, EntityType, Player}
 import org.bukkit.inventory.ItemStack
 import org.bukkit.material.Dye
 
+import java.time.LocalDate
 import java.util.Random
 import java.util.stream.IntStream
 
@@ -279,7 +280,14 @@ object BreakUtil {
   def blockCountWeight(world: World): Double = {
     val managedWorld = ManagedWorld.fromBukkitWorld(world)
     val seichiWorldFactor = if (managedWorld.exists(_.isSeichi)) 1.0 else 0.0
-    val sw01Penalty = if (managedWorld.contains(ManagedWorld.WORLD_SW)) 0.8 else 1.0
+    val sw01Penalty =
+      if (managedWorld.contains(ManagedWorld.WORLD_SW)) {
+        // 5周年記念企画のうち21億チャレンジ用の条件分岐
+        // TODO: 終わったら消去する
+        if (LocalDate.now().isEqual(LocalDate.of(2021, 7, 22))) 2.5
+        else 0.8
+      }
+      else 1.0
 
     seichiWorldFactor * sw01Penalty
   }