diff --git a/js/data/strings_en.json b/js/data/strings_en.json
index b8777a7b..6906c88e 100644
--- a/js/data/strings_en.json
+++ b/js/data/strings_en.json
@@ -394,6 +394,7 @@
 	"only_day_rank_less_than_B": "Only if Day Rank less than B",
 	"only_flag_not_sunk": "Only if Enemy Flagship not sunk",
 	"only_flag_not_sunk_tooltip": "If enemy combined fleet, does not do Night Battle if the enemy escort fleet would be fought AND Friend Fleet is not used.",
+	"offroute_before_battle": "Off-route before battle",
 	"resupply_cost": "Resupply Cost",
 	"submarine_only": "Submarine Only",
 	"add_cost": "Add Cost (% of current supply before battle)",
diff --git a/js/data/strings_ja.json b/js/data/strings_ja.json
index 212d37f5..b7af0972 100644
--- a/js/data/strings_ja.json
+++ b/js/data/strings_ja.json
@@ -394,6 +394,7 @@
 	"only_day_rank_less_than_B": "B未満なら",
 	"only_flag_not_sunk": "敵旗艦が健在なら",
 	"only_flag_not_sunk_tooltip": "敵連合艦隊第一艦隊との夜戦権が無い場合は夜戦を行わない(友軍艦隊を使用する場合を除く)",
+	"offroute_before_battle": "戦闘前帰還率",
 	"resupply_cost": "資源消費タイプ",
 	"submarine_only": "潜水艦のみ",
 	"add_cost": "追加コスト(戦闘開始前に現在の残り資源から)",
diff --git a/js/simulator-ui/convert.js b/js/simulator-ui/convert.js
index 1b45d6da..bd54a591 100644
--- a/js/simulator-ui/convert.js
+++ b/js/simulator-ui/convert.js
@@ -870,6 +870,7 @@ window.CONVERT = {
 				useAtoll: battleUI.useAtoll,
 				useSmoke: battleUI.useSmoke,
 				useAnchorageRepair: battleUI.useAnchorageRepair,
+				offrouteRate: battleUI.offrouteRate/100,
 			};
 			if (battleUI.doNBCond) nodeInput.doNBCond = battleUI.doNBCond;
 			if (battleUI.formationUseLAIfNoSpAttack && COMMON.checkSpecialAttackUI(this._UI_MAIN,+battleUI.formation)) nodeInput.formationUseLAIfNoSpAttack = true;
diff --git a/js/simulator-ui/sim-interface.js b/js/simulator-ui/sim-interface.js
index bb604a2f..9e8c046e 100644
--- a/js/simulator-ui/sim-interface.js
+++ b/js/simulator-ui/sim-interface.js
@@ -825,6 +825,10 @@ var SIM = {
 	
 		for (let battleInd=0; battleInd<dataInput.nodes.length; battleInd++) {
 			let node = dataInput.nodes[battleInd];
+			if (node.offrouteRate && Math.random() < node.offrouteRate) {
+				break;
+			}
+			
 			let isBossNode = battleInd == dataInput.nodes.length-1;
 			let fleetF = FLEETS1[0];
 			let fleetE = FLEETS2[battleInd];
diff --git a/js/simulator-ui/ui-main.js b/js/simulator-ui/ui-main.js
index 3925c5e2..e2bc1a6f 100644
--- a/js/simulator-ui/ui-main.js
+++ b/js/simulator-ui/ui-main.js
@@ -458,6 +458,7 @@ var UI_MAIN = Vue.createApp({
 				useAtoll: false,
 				useSmoke: false,
 				useAnchorageRepair: false,
+				offrouteRate: 0,
 					
 				enemyComps: [],
 			};
@@ -734,7 +735,7 @@ var UI_MAIN = Vue.createApp({
 					this.isRunningWatch = false;
 					return;
 				}
-				let found = (this.watchCondition == 'no_boss' && SIM.simResultPrev.battleNum < this.battles.length)
+				let found = SIM.simResultPrev && ((this.watchCondition == 'no_boss' && SIM.simResultPrev.battleNum < this.battles.length)
 					|| (this.watchCondition == 'boss' && SIM.simResultPrev.battleNum == this.battles.length)
 					|| (this.watchCondition == 'flagsunk' && SIM.simResultPrev.battleNum == this.battles.length && SIM.simResultPrev.result.flagsunk)
 					|| (this.watchCondition == 'S' && SIM.simResultPrev.battleNum == this.battles.length && SIM.simResultPrev.result.rank == 'S')
@@ -742,7 +743,7 @@ var UI_MAIN = Vue.createApp({
 					|| (this.watchCondition == 'B' && SIM.simResultPrev.battleNum == this.battles.length && SIM.simResultPrev.result.rank == 'B')
 					|| (this.watchCondition == 'C' && SIM.simResultPrev.battleNum == this.battles.length && SIM.simResultPrev.result.rank == 'C')
 					|| (this.watchCondition == 'D' && SIM.simResultPrev.battleNum == this.battles.length && SIM.simResultPrev.result.rank == 'D')
-					|| (this.watchCondition == 'E' && SIM.simResultPrev.battleNum == this.battles.length && SIM.simResultPrev.result.rank == 'E');
+					|| (this.watchCondition == 'E' && SIM.simResultPrev.battleNum == this.battles.length && SIM.simResultPrev.result.rank == 'E'));
 				if (!found) {
 					setTimeout(() => this._getWatch(replay,numRun),1);
 					return;
diff --git a/simulator.html b/simulator.html
index 7bd4adbf..6bd63c85 100644
--- a/simulator.html
+++ b/simulator.html
@@ -797,6 +797,9 @@ <h3>
 						<option value="B">{{$t('only_day_rank_less_than_B')}}</option>
 						<option value="flagsunk" :title="$t('only_flag_not_sunk_tooltip')">{{$t('only_flag_not_sunk')}}</option>
 					</select></label></div>
+					<div class="space">
+						<label><span class="header">{{$t('offroute_before_battle')}}: </span><input type="number" min="0" max="100" v-model.number="battle.offrouteRate" :class="{changed:!!battle.offrouteRate}"/>%</label>
+					</div>
 				</div>
 				<div>
 					<div><span class="header">{{$t('resupply_cost')}}:</span></div>