diff --git a/ext/js/language/grc/ancient-greek-processors.js b/ext/js/language/grc/ancient-greek-processors.js
new file mode 100644
index 0000000000..34e688cbfe
--- /dev/null
+++ b/ext/js/language/grc/ancient-greek-processors.js
@@ -0,0 +1,106 @@
+/*
+ * Copyright (C) 2025  Yomitan Authors
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+import {basicTextProcessorOptions, removeAlphabeticDiacritics} from '../text-processors.js';
+
+/** @type {import('language').TextProcessor<boolean>} */
+export const convertLatinToGreek = {
+    name: 'Convert latin characters to greek',
+    description: 'a → α, A → Α, b → β, B → Β, etc.',
+    options: basicTextProcessorOptions,
+    process: (str, setting) => {
+        return setting ? latinToGreek(str) : str;
+    },
+};
+
+/**
+ * @param {string} latin
+ * @returns {string}
+ */
+export function latinToGreek(latin) {
+    latin = removeAlphabeticDiacritics.process(latin, true);
+
+    const singleMap = {
+        a: 'α',
+        b: 'β',
+        g: 'γ',
+        d: 'δ',
+        e: 'ε',
+        z: 'ζ',
+        ē: 'η',
+        i: 'ι',
+        k: 'κ',
+        l: 'λ',
+        m: 'μ',
+        n: 'ν',
+        x: 'ξ',
+        o: 'ο',
+        p: 'π',
+        r: 'ρ',
+        s: 'σ',
+        t: 'τ',
+        u: 'υ',
+        ō: 'ω',
+        A: 'Α',
+        B: 'Β',
+        G: 'Γ',
+        D: 'Δ',
+        E: 'Ε',
+        Z: 'Ζ',
+        Ē: 'Η',
+        I: 'Ι',
+        K: 'Κ',
+        L: 'Λ',
+        M: 'Μ',
+        N: 'Ν',
+        X: 'Ξ',
+        O: 'Ο',
+        P: 'Π',
+        R: 'Ρ',
+        S: 'Σ',
+        T: 'Τ',
+        U: 'Υ',
+        Ō: 'Ω',
+    };
+
+    const doubleMap = {
+        th: 'θ',
+        ph: 'φ',
+        ch: 'χ',
+        ps: 'ψ',
+        Th: 'Θ',
+        Ph: 'Φ',
+        Ch: 'Χ',
+        Ps: 'Ψ',
+    };
+
+    let result = latin;
+
+    for (const [double, greek] of Object.entries(doubleMap)) {
+        result = result.replace(new RegExp(double, 'g'), greek);
+    }
+
+    // Handle basic character replacements
+    for (const [single, greek] of Object.entries(singleMap)) {
+        result = result.replace(new RegExp(single, 'g'), greek);
+    }
+
+    // Handle final sigma
+    result = result.replace(/σ$/, 'ς');
+
+    return result;
+}
diff --git a/ext/js/language/grc/ancient-greek-transforms.js b/ext/js/language/grc/ancient-greek-transforms.js
new file mode 100644
index 0000000000..c9ccb99ff0
--- /dev/null
+++ b/ext/js/language/grc/ancient-greek-transforms.js
@@ -0,0 +1,120 @@
+/*
+ * Copyright (C) 2025  Yomitan Authors
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+import {suffixInflection} from '../language-transforms.js';
+
+const conditions = {
+    v: {
+        name: 'Verb',
+        isDictionaryForm: true,
+    },
+    n: {
+        name: 'Noun',
+        isDictionaryForm: true,
+    },
+    adj: {
+        name: 'Adjective',
+        isDictionaryForm: true,
+    },
+};
+
+/** @type {import('language-transformer').LanguageTransformDescriptor<keyof typeof conditions>} */
+export const ancientGreekTransforms = {
+    language: 'grc',
+    conditions,
+    transforms: {
+        // inflections
+        // verbs
+        '3rd person singular present active indicative': {
+            name: '3rd person singular present active indicative',
+            rules: [
+                suffixInflection('ει', 'ω', [], ['v']),
+                suffixInflection('ει', 'εω', [], ['v']),
+            ],
+        },
+
+        // nouns
+        'accusative singular': {
+            name: 'accusative singular',
+            rules: [
+                suffixInflection('ον', 'ος', [], ['n']),
+            ],
+        },
+        'genitive singular': {
+            name: 'genitive singular',
+            rules: [
+                suffixInflection('ου', 'ος', [], ['n']),
+            ],
+        },
+        'dative singular': {
+            name: 'dative singular',
+            rules: [
+                suffixInflection('ω', 'ος', [], ['n']),
+            ],
+        },
+        'vocative singular': {
+            name: 'vocative singular',
+            rules: [
+                suffixInflection('ε', 'ος', [], ['n']),
+            ],
+        },
+        'nominative plural': {
+            name: 'nominative plural',
+            rules: [
+                suffixInflection('οι', 'ος', [], ['n']),
+            ],
+        },
+        'genitive plural': {
+            name: 'genitive plural',
+            rules: [
+                suffixInflection('ων', 'ος', [], ['n']),
+            ],
+        },
+        'dative plural': {
+            name: 'dative plural',
+            rules: [
+                suffixInflection('οις', 'ος', [], ['n']),
+            ],
+        },
+        'accusative plural': {
+            name: 'accusative plural',
+            rules: [
+                suffixInflection('ους', 'ος', [], ['n']),
+            ],
+        },
+        'vocative plural': {
+            name: 'vocative plural',
+            rules: [
+                suffixInflection('οι', 'ος', [], ['n']),
+            ],
+        },
+        // adjectives
+        'accusative singular masculine': {
+            name: 'accusative singular masculine',
+            rules: [
+                suffixInflection('ον', 'ος', [], ['adj']),
+            ],
+        },
+        // word formation
+        'nominalization': {
+            name: 'nominalization',
+            rules: [
+                suffixInflection('ος', 'εω', [], ['v']),
+            ],
+        },
+    },
+};
diff --git a/ext/js/language/language-descriptors.js b/ext/js/language/language-descriptors.js
index 79d12f5ea8..164a2b8564 100644
--- a/ext/js/language/language-descriptors.js
+++ b/ext/js/language/language-descriptors.js
@@ -25,6 +25,8 @@ import {esperantoTransforms} from './eo/esperanto-transforms.js';
 import {spanishTransforms} from './es/spanish-transforms.js';
 import {apostropheVariants} from './fr/french-text-preprocessors.js';
 import {frenchTransforms} from './fr/french-transforms.js';
+import {convertLatinToGreek} from './grc/ancient-greek-processors.js';
+import {ancientGreekTransforms} from './grc/ancient-greek-transforms.js';
 import {
     alphabeticToHiragana,
     alphanumericWidthVariants,
@@ -177,7 +179,9 @@ const languageDescriptors = [
         textPreprocessors: {
             ...capitalizationPreprocessors,
             removeAlphabeticDiacritics,
+            convertLatinToGreek,
         },
+        languageTransforms: ancientGreekTransforms,
     },
     {
         iso: 'hi',
diff --git a/test/language/ancient-greek-processors.test.js b/test/language/ancient-greek-processors.test.js
new file mode 100644
index 0000000000..d76e942348
--- /dev/null
+++ b/test/language/ancient-greek-processors.test.js
@@ -0,0 +1,30 @@
+/*
+ * Copyright (C) 2025  Yomitan Authors
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+import {describe, expect, test} from 'vitest';
+import {latinToGreek} from '../../ext/js/language/grc/ancient-greek-processors.js';
+
+
+const testCases = [
+    ['Zeus', 'Ζευς'],
+];
+
+describe('diacritics normalization', () => {
+    test.each(testCases)('%s converts to %s', (input, expected) => {
+        expect(latinToGreek(input)).toStrictEqual(expected);
+    });
+});
diff --git a/test/language/ancient-greek-transforms.test.js b/test/language/ancient-greek-transforms.test.js
new file mode 100644
index 0000000000..ecc8add44a
--- /dev/null
+++ b/test/language/ancient-greek-transforms.test.js
@@ -0,0 +1,61 @@
+/*
+ * Copyright (C) 2025  Yomitan Authors
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+import {ancientGreekTransforms} from '../../ext/js/language/grc/ancient-greek-transforms.js';
+import {LanguageTransformer} from '../../ext/js/language/language-transformer.js';
+import {testLanguageTransformer} from '../fixtures/language-transformer-test.js';
+
+/* eslint-disable @stylistic/no-multi-spaces */
+const tests = [
+    {
+        category: 'verbs',
+        valid: true,
+        tests: [
+            {term: 'λύω',   source: 'λύει',    rule: 'v',   reasons: ['3rd person singular present active indicative']},
+            {term: 'φιλεω', source: 'φιλει',   rule: 'v',   reasons: ['3rd person singular present active indicative']},
+            {term: 'γεωργεω', source: 'γεωργος', rule: 'v',   reasons: ['nominalization']},
+        ],
+    },
+    {
+        category: 'nouns',
+        valid: true,
+        tests: [
+            {term: 'ανθρωπος', source: 'ανθρωπον', rule: 'n', reasons: ['accusative singular']},
+            {term: 'ανθρωπος', source: 'ανθρωπου', rule: 'n', reasons: ['genitive singular']},
+            {term: 'ανθρωπος', source: 'ανθρωπε', rule: 'n', reasons: ['vocative singular']},
+            {term: 'ανθρωπος', source: 'ανθρωπω', rule: 'n', reasons: ['dative singular']},
+            {term: 'ανθρωπος', source: 'ανθρωποι', rule: 'n', reasons: ['nominative plural']},
+            {term: 'ανθρωπος', source: 'ανθρωποις', rule: 'n', reasons: ['dative plural']},
+            {term: 'ανθρωπος', source: 'ανθρωπους', rule: 'n', reasons: ['accusative plural']},
+            {term: 'ανθρωπος', source: 'ανθρωπων', rule: 'n', reasons: ['genitive plural']},
+            {term: 'ανθρωπος', source: 'ανθρωποι', rule: 'n', reasons: ['vocative plural']},
+        ],
+    },
+    {
+        category: 'adjectives',
+        valid: true,
+        tests: [
+            {term: 'καλος', source: 'καλον', rule: 'adj', reasons: ['accusative singular masculine']},
+        ],
+    },
+];
+/* eslint-enable @stylistic/no-multi-spaces */
+
+const languageTransformer = new LanguageTransformer();
+languageTransformer.addDescriptor(ancientGreekTransforms);
+
+testLanguageTransformer(languageTransformer, tests);
diff --git a/types/ext/language-descriptors.d.ts b/types/ext/language-descriptors.d.ts
index 70cedb3e0d..b39bb82047 100644
--- a/types/ext/language-descriptors.d.ts
+++ b/types/ext/language-descriptors.d.ts
@@ -121,7 +121,9 @@ type AllTextProcessors = {
         };
     };
     grc: {
-        pre: CapitalizationPreprocessors & AlphabeticDiacriticsProcessor;
+        pre: CapitalizationPreprocessors & AlphabeticDiacriticsProcessor & {
+            convertLatinToGreek: TextProcessor<boolean>;
+        };
     };
     hi: Record<string, never>;
     hu: {