diff --git a/config.example.jsonc b/config.example.jsonc
index 0938591d..6768f57f 100644
--- a/config.example.jsonc
+++ b/config.example.jsonc
@@ -433,6 +433,12 @@
     "nameMatchColor": "#f5bde6", // Hex color used when a subtitle token matches an entry from the SubMiner character dictionary.
     "nPlusOneColor": "#c6a0f6", // Color used for the single N+1 target token subtitle highlight.
     "knownWordColor": "#a6da95", // Color used for known-word subtitle highlights.
+    "knownWordMaturityColors": {
+      "new": "#ee99a0", // Color for known words whose Anki cards are new (never reviewed), when maturity highlighting is enabled.
+      "learning": "#b7bdf8", // Color for known words whose Anki cards are in (re)learning, when maturity highlighting is enabled.
+      "young": "#91d7e3", // Color for known words whose Anki cards are in review below the mature threshold, when maturity highlighting is enabled.
+      "mature": "#a6da95" // Color for known words whose Anki cards are at or above the mature interval threshold, when maturity highlighting is enabled.
+    }, // Known word maturity colors setting.
     "jlptColors": {
       "N1": "#ed8796", // N1 setting.
       "N2": "#f5a97f", // N2 setting.
@@ -569,6 +575,8 @@
     }, // Media setting.
     "knownWords": {
       "highlightEnabled": false, // Enable fast local highlighting for words already known in Anki. Values: true | false
+      "maturityEnabled": false, // Color known-word highlights by Anki card maturity (new, learning, young, mature) instead of a single color. Requires known-word highlighting. Values: true | false
+      "matureThresholdDays": 21, // Card interval in days at which a known word counts as mature (Anki convention: 21).
       "refreshMinutes": 1440, // Minutes between known-word cache refreshes.
       "addMinedWordsImmediately": true, // Immediately append newly mined card words into the known-word cache. Values: true | false
       "matchMode": "headword", // Known-word matching strategy for subtitle annotations. Cache matches always receive known-word highlighting even when POS filters suppress other annotation types. Values: headword | surface
diff --git a/docs-site/public/config.example.jsonc b/docs-site/public/config.example.jsonc
index 0938591d..6768f57f 100644
--- a/docs-site/public/config.example.jsonc
+++ b/docs-site/public/config.example.jsonc
@@ -433,6 +433,12 @@
     "nameMatchColor": "#f5bde6", // Hex color used when a subtitle token matches an entry from the SubMiner character dictionary.
     "nPlusOneColor": "#c6a0f6", // Color used for the single N+1 target token subtitle highlight.
     "knownWordColor": "#a6da95", // Color used for known-word subtitle highlights.
+    "knownWordMaturityColors": {
+      "new": "#ee99a0", // Color for known words whose Anki cards are new (never reviewed), when maturity highlighting is enabled.
+      "learning": "#b7bdf8", // Color for known words whose Anki cards are in (re)learning, when maturity highlighting is enabled.
+      "young": "#91d7e3", // Color for known words whose Anki cards are in review below the mature threshold, when maturity highlighting is enabled.
+      "mature": "#a6da95" // Color for known words whose Anki cards are at or above the mature interval threshold, when maturity highlighting is enabled.
+    }, // Known word maturity colors setting.
     "jlptColors": {
       "N1": "#ed8796", // N1 setting.
       "N2": "#f5a97f", // N2 setting.
@@ -569,6 +575,8 @@
     }, // Media setting.
     "knownWords": {
       "highlightEnabled": false, // Enable fast local highlighting for words already known in Anki. Values: true | false
+      "maturityEnabled": false, // Color known-word highlights by Anki card maturity (new, learning, young, mature) instead of a single color. Requires known-word highlighting. Values: true | false
+      "matureThresholdDays": 21, // Card interval in days at which a known word counts as mature (Anki convention: 21).
       "refreshMinutes": 1440, // Minutes between known-word cache refreshes.
       "addMinedWordsImmediately": true, // Immediately append newly mined card words into the known-word cache. Values: true | false
       "matchMode": "headword", // Known-word matching strategy for subtitle annotations. Cache matches always receive known-word highlighting even when POS filters suppress other annotation types. Values: headword | surface
diff --git a/src/anki-integration/known-word-cache-maturity.test.ts b/src/anki-integration/known-word-cache-maturity.test.ts
index 6128af49..7eedd3e8 100644
--- a/src/anki-integration/known-word-cache-maturity.test.ts
+++ b/src/anki-integration/known-word-cache-maturity.test.ts
@@ -5,6 +5,7 @@ import os from 'node:os';
 import path from 'node:path';
 
 import type { AnkiConnectConfig } from '../types/anki';
+import { setLogLevel } from '../logger';
 import { KnownWordCacheManager, getKnownWordCacheLifecycleConfig } from './known-word-cache';
 
 interface HarnessNoteInfo {
@@ -255,8 +256,14 @@ test('getKnownWordTier returns null and skips tier queries when maturity is disa
 
 test('refresh preserves known-word cache when maturity lookup fails', async () => {
   const { manager, statePath, clientState, cleanup } = createMaturityHarness(maturityConfig());
+  const originalInfo = console.info;
+  const infoLogs: string[] = [];
+  setLogLevel('info');
 
   try {
+    console.info = (...args: unknown[]) => {
+      infoLogs.push(args.map((value) => String(value)).join(' '));
+    };
     clientState.findNotesByQuery.set('deck:"Mining"', [1]);
     clientState.failedQueries.add('deck:"Mining" prop:ivl>=21');
     clientState.notesInfoResult = [{ noteId: 1, fields: { Word: { value: '猫' } } }];
@@ -271,7 +278,10 @@ test('refresh preserves known-word cache when maturity lookup fails', async () =
     };
     assert.equal(persisted.version, 4);
     assert.deepEqual(persisted.tiers, {});
+    assert.match(infoLogs.join('\n'), /maturityTiers=fetch-failed/);
   } finally {
+    console.info = originalInfo;
+    setLogLevel(undefined);
     cleanup();
   }
 });
diff --git a/src/anki-integration/known-word-cache.ts b/src/anki-integration/known-word-cache.ts
index 6c130850..5a9c2b71 100644
--- a/src/anki-integration/known-word-cache.ts
+++ b/src/anki-integration/known-word-cache.ts
@@ -389,8 +389,10 @@ export class KnownWordCacheManager {
     this.isRefreshingKnownWords = true;
     try {
       const noteFieldsById = await this.fetchKnownWordNoteFieldsById();
+      const maturityTrackingEnabled = this.isMaturityTrackingEnabled();
+      let maturityFetchFailed = false;
       let tierSets = null;
-      if (this.isMaturityTrackingEnabled()) {
+      if (maturityTrackingEnabled) {
         try {
           tierSets = await fetchKnownWordMaturityTierSets(
             (query, options) => this.deps.client.findNotes(query, options),
@@ -398,6 +400,7 @@ export class KnownWordCacheManager {
             getMatureIntervalThresholdDays(this.deps.getConfig()),
           );
         } catch (error) {
+          maturityFetchFailed = true;
           log.warn('Failed to fetch known-word maturity tiers:', (error as Error).message);
         }
       }
@@ -441,7 +444,11 @@ export class KnownWordCacheManager {
         'Known-word cache refreshed',
         `noteCount=${currentNoteIds.length}`,
         `wordCount=${this.wordReadingNoteIds.size}`,
-        tierSets ? `maturityTiers=${this.noteTierById.size}` : 'maturityTiers=off',
+        tierSets
+          ? `maturityTiers=${this.noteTierById.size}`
+          : maturityFetchFailed
+            ? 'maturityTiers=fetch-failed'
+            : 'maturityTiers=off',
       );
     } catch (error) {
       log.warn('Failed to refresh known-word cache:', (error as Error).message);
diff --git a/src/anki-integration/known-word-maturity.test.ts b/src/anki-integration/known-word-maturity.test.ts
index f04a1bae..d6be6314 100644
--- a/src/anki-integration/known-word-maturity.test.ts
+++ b/src/anki-integration/known-word-maturity.test.ts
@@ -35,20 +35,11 @@ test('maturity is enabled only when both highlight and maturity flags are on', (
 
 test('mature threshold falls back to default for invalid values', () => {
   assert.equal(DEFAULT_MATURE_INTERVAL_THRESHOLD_DAYS, 21);
-  assert.equal(
-    getMatureIntervalThresholdDays(makeConfig({ matureThresholdDays: 30 })),
-    30,
-  );
-  assert.equal(
-    getMatureIntervalThresholdDays(makeConfig({ matureThresholdDays: 14.9 })),
-    14,
-  );
+  assert.equal(getMatureIntervalThresholdDays(makeConfig({ matureThresholdDays: 30 })), 30);
+  assert.equal(getMatureIntervalThresholdDays(makeConfig({ matureThresholdDays: 14.9 })), 14);
   assert.equal(getMatureIntervalThresholdDays(makeConfig({ matureThresholdDays: 0 })), 21);
   assert.equal(getMatureIntervalThresholdDays(makeConfig({ matureThresholdDays: -5 })), 21);
-  assert.equal(
-    getMatureIntervalThresholdDays(makeConfig({ matureThresholdDays: Number.NaN })),
-    21,
-  );
+  assert.equal(getMatureIntervalThresholdDays(makeConfig({ matureThresholdDays: Number.NaN })), 21);
   assert.equal(getMatureIntervalThresholdDays(makeConfig({})), 21);
   assert.equal(getMatureIntervalThresholdDays(makeConfig(undefined)), 21);
 });
diff --git a/src/core/services/tokenizer/annotation-stage-maturity.test.ts b/src/core/services/tokenizer/annotation-stage-maturity.test.ts
index 49541295..591bebd1 100644
--- a/src/core/services/tokenizer/annotation-stage-maturity.test.ts
+++ b/src/core/services/tokenizer/annotation-stage-maturity.test.ts
@@ -80,9 +80,7 @@ test('annotateTokens resolves maturity through the kana reading fallback', () =>
     reading: string | undefined;
     allowReadingOnlyMatch: boolean | undefined;
   }> = [];
-  const tokens = [
-    makeToken({ surface: '大体', headword: '大体', reading: 'だいたい', endPos: 2 }),
-  ];
+  const tokens = [makeToken({ surface: '大体', headword: '大体', reading: 'だいたい', endPos: 2 })];
 
   const result = annotateTokens(
     tokens,
diff --git a/src/core/services/tokenizer/annotation-stage.ts b/src/core/services/tokenizer/annotation-stage.ts
index 558e065d..a0cca85a 100644
--- a/src/core/services/tokenizer/annotation-stage.ts
+++ b/src/core/services/tokenizer/annotation-stage.ts
@@ -646,7 +646,9 @@ function computeTokenKnownMaturity(
   if (!fallbackReading || fallbackReading === matchText.trim()) {
     return undefined;
   }
-  return getKnownWordTier(fallbackReading, undefined, { allowReadingOnlyMatch: false }) ?? undefined;
+  return (
+    getKnownWordTier(fallbackReading, undefined, { allowReadingOnlyMatch: false }) ?? undefined
+  );
 }
 
 function filterTokenFrequencyRank(
diff --git a/src/renderer/subtitle-render-word-class.test.ts b/src/renderer/subtitle-render-word-class.test.ts
index e151620a..205e5d34 100644
--- a/src/renderer/subtitle-render-word-class.test.ts
+++ b/src/renderer/subtitle-render-word-class.test.ts
@@ -250,8 +250,5 @@ test('computeWordClass gives n+1 and name matches precedence over maturity', ()
     surface: 'アクア',
   }) as MergedToken & { isNameMatch?: boolean };
   nameMatch.isNameMatch = true;
-  assert.equal(
-    computeWordClass(nameMatch, { nameMatchEnabled: true }),
-    'word word-name-match',
-  );
+  assert.equal(computeWordClass(nameMatch, { nameMatchEnabled: true }), 'word word-name-match');
 });