diff --git a/src/GameFetcher.ts b/src/GameFetcher.ts
index 428e541..7709b46 100644
--- a/src/GameFetcher.ts
+++ b/src/GameFetcher.ts
@@ -137,17 +137,30 @@ export class GameFetcher {
         type: "CoopInfo",
         listNode: null,
         groupInfo: null,
+        gradeBefore: null,
       };
     }
 
     const { historyDetails, ...groupInfo } = group;
-    const listNode = historyDetails.nodes.find((i) => i.id === id) ??
+    const listNodeIdx = historyDetails.nodes.findIndex((i) => i.id === id) ??
       null;
+    const listNode = listNodeIdx !== null
+      ? historyDetails.nodes[listNodeIdx]
+      : null;
+    const listNodeBefore = listNodeIdx !== null
+      ? (historyDetails.nodes[listNodeIdx + 1] ?? null)
+      : null;
 
     return {
       type: "CoopInfo",
       listNode,
       groupInfo,
+      gradeBefore: listNodeBefore?.afterGrade && listNodeBefore.afterGradePoint
+        ? {
+          grade: listNodeBefore.afterGrade,
+          gradePoint: listNodeBefore.afterGradePoint,
+        }
+        : null,
     };
   }
   async getBattleMetaById(
diff --git a/src/exporters/stat.ink.ts b/src/exporters/stat.ink.ts
index e11d8ff..cd678e6 100644
--- a/src/exporters/stat.ink.ts
+++ b/src/exporters/stat.ink.ts
@@ -686,6 +686,7 @@ export class StatInkExporter implements GameExporter {
   }
   async mapCoop(
     {
+      gradeBefore,
       groupInfo,
       detail,
     }: CoopInfo,
@@ -732,25 +733,33 @@ export class StatInkExporter implements GameExporter {
 
     let title_before: string | undefined = undefined;
     let title_exp_before: number | undefined = undefined;
-    const expDiff = COOP_POINT_MAP[clear_waves];
 
-    if (
-      nonNullable(title_after) && nonNullable(title_exp_after) &&
-      nonNullable(expDiff)
-    ) {
-      if (title_exp_after === 40 && expDiff === 20) {
-        // 20 -> 40 or ?(rank up) -> 40
-      } else if (title_exp_after === 40 && expDiff < 0 && title_after !== "8") {
-        // 60,50 -> 40 or ?(rank down) to 40
-      } else if (title_exp_after === 999 && expDiff !== 0) {
-        // 980,990 -> 999
-        title_before = title_after;
-      } else {
-        if (title_exp_after - expDiff >= 0) {
+    if (gradeBefore) {
+      title_before = b64Number(gradeBefore.grade.id).toString();
+      title_exp_before = gradeBefore.gradePoint;
+    } else {
+      const expDiff = COOP_POINT_MAP[clear_waves];
+
+      if (
+        nonNullable(title_after) && nonNullable(title_exp_after) &&
+        nonNullable(expDiff)
+      ) {
+        if (title_exp_after === 40 && expDiff === 20) {
+          // 20 -> 40 or ?(rank up) -> 40
+        } else if (
+          title_exp_after === 40 && expDiff < 0 && title_after !== "8"
+        ) {
+          // 60,50 -> 40 or ?(rank down) to 40
+        } else if (title_exp_after === 999 && expDiff !== 0) {
+          // 980,990 -> 999
           title_before = title_after;
-          title_exp_before = title_exp_after - expDiff;
         } else {
-          title_before = (parseInt(title_after) - 1).toString();
+          if (title_exp_after - expDiff >= 0) {
+            title_before = title_after;
+            title_exp_before = title_exp_after - expDiff;
+          } else {
+            title_before = (parseInt(title_after) - 1).toString();
+          }
         }
       }
     }
diff --git a/src/types.ts b/src/types.ts
index c58add7..4af3ba6 100644
--- a/src/types.ts
+++ b/src/types.ts
@@ -77,6 +77,11 @@ export type BattleListNode = {
 };
 export type CoopListNode = {
   id: string;
+  afterGrade: null | {
+    "name": string;
+    "id": string;
+  };
+  afterGradePoint: null | number;
 };
 export type HistoryGroupItem<T> = {
   bankaraMatchChallenge: null | BankaraMatchChallenge;
@@ -193,6 +198,13 @@ export type CoopInfo = {
   listNode: null | CoopListNode;
   groupInfo: null | Omit<CoopHistoryGroup, "historyDetails">;
   detail: CoopHistoryDetail;
+  gradeBefore: null | {
+    grade: {
+      name: string;
+      id: string;
+    };
+    gradePoint: number;
+  };
 };
 export type Game = VsInfo | CoopInfo;
 export type VsMode = "REGULAR" | "BANKARA" | "PRIVATE" | "FEST" | "X_MATCH";