diff --git a/src/idz/userdb/decoder/saveProfile2.ts b/src/idz/userdb/decoder/saveProfile2.ts
index 60dbbcf..b0bd220 100644
--- a/src/idz/userdb/decoder/saveProfile2.ts
+++ b/src/idz/userdb/decoder/saveProfile2.ts
@@ -1,6 +1,7 @@
 import { car } from "./_car";
 import { mission } from "./_mission";
 import { BackgroundCode, CourseNo, TitleCode } from "../model/base";
+import { StoryCell, StoryRow } from "../model/story";
 import { SaveProfileRequest } from "../request/saveProfile";
 import { bitmap } from "./_bitmap";
 import { AimeId } from "../../../model";
@@ -9,10 +10,10 @@ saveProfile2.msgCode = 0x0068;
 saveProfile2.msgLen = 0x0940;
 
 export function saveProfile2(buf: Buffer): SaveProfileRequest {
-  const storyRows = new Array();
+  const storyRows = new Map<number, StoryRow>();
 
   for (let i = 0; i < 9; i++) {
-    const cells = new Array();
+    const cells = new Map<number, StoryCell>();
     const rowOffset = 0x01a8 + i * 0x3c;
 
     for (let j = 0; j < 9; j++) {
@@ -20,12 +21,12 @@ export function saveProfile2(buf: Buffer): SaveProfileRequest {
       const b = buf.readUInt16LE(rowOffset + 0x28 + j * 2);
       const cell = { a, b };
 
-      cells.push(cell);
+      cells.set(j, cell);
     }
 
     const row = { cells };
 
-    storyRows.push(row);
+    storyRows.set(i, row);
   }
 
   const coursePlays = new Map<CourseNo, number>();
diff --git a/src/idz/userdb/decoder/saveProfile3.ts b/src/idz/userdb/decoder/saveProfile3.ts
index 0d8876f..59eb230 100644
--- a/src/idz/userdb/decoder/saveProfile3.ts
+++ b/src/idz/userdb/decoder/saveProfile3.ts
@@ -1,6 +1,7 @@
 import { car } from "./_car";
 import { mission } from "./_mission";
 import { BackgroundCode, CourseNo, TitleCode } from "../model/base";
+import { StoryCell, StoryRow } from "../model/story";
 import { SaveProfileRequest } from "../request/saveProfile";
 import { bitmap } from "./_bitmap";
 import { AimeId } from "../../../model";
@@ -9,12 +10,12 @@ saveProfile3.msgCode = 0x0138;
 saveProfile3.msgLen = 0x0a70;
 
 export function saveProfile3(buf: Buffer): SaveProfileRequest {
-  const storyRows = new Array();
+  const storyRows = new Map<number, StoryRow>();
 
   // Story layout has changed somewhat...
 
   for (let i = 0; i < 27; i++) {
-    const cells = new Array();
+    const cells = new Map<number, StoryCell>();
     const rowOffset = 0x01ac + i * 0x18;
 
     for (let j = 0; j < 9; j++) {
@@ -22,12 +23,12 @@ export function saveProfile3(buf: Buffer): SaveProfileRequest {
       const b = buf.readUInt8(rowOffset + 0x09 + j);
       const cell = { a, b };
 
-      cells.push(cell);
+      cells.set(j, cell);
     }
 
     const row = { cells };
 
-    storyRows.push(row);
+    storyRows.set(i, row);
   }
 
   const coursePlays = new Map<CourseNo, number>();
diff --git a/src/idz/userdb/encoder/loadProfile2.ts b/src/idz/userdb/encoder/loadProfile2.ts
index 5450351..4ab8757 100644
--- a/src/idz/userdb/encoder/loadProfile2.ts
+++ b/src/idz/userdb/encoder/loadProfile2.ts
@@ -37,14 +37,22 @@ export function loadProfile2(res: LoadProfileResponse) {
     }
   }
 
-  for (let i = 0; i < 9 && i < res.story.rows.length; i++) {
-    const row = res.story.rows[i];
+  for (let i = 0; i < 9; i++) {
+    const row = res.story.rows.get(i);
     const rowOffset = 0x0228 + i * 0x26;
 
-    for (let j = 0; j < 9 && j < row.cells.length; j++) {
-      const cell = row.cells[j];
+    if (row === undefined) {
+      continue;
+    }
+
+    for (let j = 0; j < 9; j++) {
+      const cell = row.cells.get(j);
       const cellOffset = rowOffset + j * 4;
 
+      if (cell === undefined) {
+        continue;
+      }
+
       buf.writeUInt16LE(cell.a, cellOffset + 0);
       buf.writeUInt16LE(cell.b, cellOffset + 2);
     }
diff --git a/src/idz/userdb/encoder/loadProfile3.ts b/src/idz/userdb/encoder/loadProfile3.ts
index 0841840..cbb543f 100644
--- a/src/idz/userdb/encoder/loadProfile3.ts
+++ b/src/idz/userdb/encoder/loadProfile3.ts
@@ -37,14 +37,22 @@ export function loadProfile3(res: LoadProfileResponse) {
   // space for story cells, and 27 rows * 19 bytes per row = 513 bytes, which
   // is the max that will fit (the final byte of each row is unused).
 
-  for (let i = 0; i < 27 && i < res.story.rows.length; i++) {
-    const row = res.story.rows[i];
+  for (let i = 0; i < 27; i++) {
+    const row = res.story.rows.get(i);
     const rowOffset = 0x0256 + i * 0x13;
 
-    for (let j = 0; j < 9 && j < row.cells.length; j++) {
-      const cell = row.cells[j];
+    if (row === undefined) {
+      continue;
+    }
+
+    for (let j = 0; j < 9; j++) {
+      const cell = row.cells.get(j);
       const cellOffset = rowOffset + j * 2;
 
+      if (cell === undefined) {
+        continue;
+      }
+
       buf.writeUInt8(cell.a, cellOffset + 0);
       buf.writeUInt8(cell.b, cellOffset + 1);
     }
diff --git a/src/idz/userdb/handler/createProfile.ts b/src/idz/userdb/handler/createProfile.ts
index 2b997f6..75b3138 100644
--- a/src/idz/userdb/handler/createProfile.ts
+++ b/src/idz/userdb/handler/createProfile.ts
@@ -1,7 +1,7 @@
 import { MissionState } from "../model/mission";
 import { Profile } from "../model/profile";
 import { Settings } from "../model/settings";
-import { Story } from "../model/story";
+import { Story, StoryRow } from "../model/story";
 import { Unlocks } from "../model/unlocks";
 import { CreateProfileRequest } from "../request/createProfile";
 import { CreateProfileResponse } from "../response/createProfile";
@@ -35,7 +35,11 @@ export async function createProfile(
     paperCup: 0,
     gauges: 5,
   };
-  const story: Story = { x: 0, y: 0, rows: [] };
+  const story: Story = {
+    x: 0,
+    y: 0,
+    rows: new Map<number, StoryRow>(),
+  };
   const unlocks: Unlocks = {
     auras: 1,
     cup: 0,
diff --git a/src/idz/userdb/model/story.ts b/src/idz/userdb/model/story.ts
index 9cff2c6..296177c 100644
--- a/src/idz/userdb/model/story.ts
+++ b/src/idz/userdb/model/story.ts
@@ -4,11 +4,11 @@ export interface StoryCell {
 }
 
 export interface StoryRow {
-  cells: StoryCell[];
+  cells: Map<number, StoryCell>;
 }
 
 export interface Story {
   x: number;
   y: number;
-  rows: StoryRow[];
+  rows: Map<number, StoryRow>;
 }
diff --git a/src/idz/userdb/sql/story.ts b/src/idz/userdb/sql/story.ts
index 758ed04..8eada11 100644
--- a/src/idz/userdb/sql/story.ts
+++ b/src/idz/userdb/sql/story.ts
@@ -6,6 +6,21 @@ import { FacetRepository } from "../repo";
 import { Id } from "../../../model";
 import { Transaction } from "../../../sql";
 
+function cellChanged(
+  lhs: StoryCell | undefined,
+  rhs: StoryCell | undefined
+): boolean {
+  if (!lhs) {
+    return true;
+  }
+
+  if (!rhs) {
+    return true;
+  }
+
+  return lhs.a !== rhs.a || lhs.b !== rhs.b;
+}
+
 export class SqlStoryRepository implements FacetRepository<Story> {
   constructor(private readonly _txn: Transaction) {}
 
@@ -19,22 +34,12 @@ export class SqlStoryRepository implements FacetRepository<Story> {
 
     // Must succeed even if nonexistent (required by save method below)
 
-    const result = {
+    const result: Story = {
       x: header !== undefined ? parseInt(header.x!) : 0,
       y: header !== undefined ? parseInt(header.y!) : 0,
-      rows: new Array<StoryRow>(),
+      rows: new Map<number, StoryRow>(),
     };
 
-    for (let i = 0; i < 27; i++) {
-      const row: StoryRow = { cells: new Array<StoryCell>() };
-
-      for (let j = 0; j < 9; j++) {
-        row.cells.push({ a: 0, b: 0 });
-      }
-
-      result.rows.push(row);
-    }
-
     const loadCellSql = sql
       .select("sc.*")
       .from("idz_story_cell_state sc")
@@ -45,7 +50,23 @@ export class SqlStoryRepository implements FacetRepository<Story> {
     for (const row of rows) {
       const rowNo = parseInt(row.row_no!);
       const colNo = parseInt(row.col_no!);
-      const cell = result.rows[rowNo].cells[colNo];
+
+      if (!result.rows.has(rowNo)) {
+        result.rows.set(rowNo, {
+          cells: new Map<number, StoryCell>(),
+        });
+      }
+
+      const gridRow = result.rows.get(rowNo)!;
+
+      if (gridRow.cells.has(colNo)) {
+        gridRow.cells.set(colNo, {
+          a: 0,
+          b: 0,
+        });
+      }
+
+      const cell = gridRow.cells.get(colNo)!;
 
       cell.a = parseInt(row.a!);
       cell.b = parseInt(row.b!);
@@ -68,15 +89,15 @@ export class SqlStoryRepository implements FacetRepository<Story> {
 
     await this._txn.modify(headSql);
 
-    for (let i = 0; i < story.rows.length; i++) {
-      const exRow = existing.rows[i];
-      const row = story.rows[i];
+    for (const i of story.rows.keys()) {
+      const exRow = existing.rows.get(i);
+      const row = story.rows.get(i)!;
 
-      for (let j = 0; j < row.cells.length; j++) {
-        const exCell = exRow.cells[j];
-        const cell = row.cells[j];
+      for (const j of row.cells.keys()) {
+        const exCell = exRow !== undefined ? exRow.cells.get(j) : undefined;
+        const cell = row.cells.get(j)!;
 
-        if (cell.a === exCell.a && cell.b === exCell.b) {
+        if (!cellChanged(cell, exCell)) {
           continue; // Most if not all cells are unchanged on profile save.
         }