diff --git a/app/src/main/kotlin/jackall/moncalc/activity/MainActivity.kt b/app/src/main/kotlin/jackall/moncalc/activity/MainActivity.kt
index 2033338..b29cd72 100644
--- a/app/src/main/kotlin/jackall/moncalc/activity/MainActivity.kt
+++ b/app/src/main/kotlin/jackall/moncalc/activity/MainActivity.kt
@@ -67,15 +67,20 @@
                 dateRandom.add(dateEnd.get(Calendar.DATE), -Random().nextInt(dateDiff.toInt()))
 
                 val drops = RealmList<Drop>()
-                val grade = Random().nextInt(6)
+                val gradeId =
+                        if (Math.random() < 0.1) {
+                            Random().nextInt(3) + 3
+                        } else {
+                            Random().nextInt(3)
+                        }
                 drops.add(
                         Drop(
                                 fruitId = Random().nextInt(15),
-                                gradeId = grade
+                                gradeId = gradeId
                         )
                 )
                 var specialCount: Int
-                if (grade >= 3) {
+                if (gradeId >= 3) {
                     specialCount = 1
                 } else {
                     specialCount = 0