diff --git a/kanken_online/__init__.py b/kanken_online/__init__.py
index 82f40b2..65463e2 100644
--- a/kanken_online/__init__.py
+++ b/kanken_online/__init__.py
@@ -1,5 +1,5 @@
 import os
-from flask import Flask, render_template, g
+from flask import Flask, redirect, render_template, g, request, session
 from pathlib import Path
 from .auth import login_required
 
@@ -31,11 +31,19 @@ def create_app(test_config=None):
     @app.route("/about")
     def about_page():
         return render_template("about.html")
+
+    def update_settings(form):
+        session["language"] = form["language"]
+        session["theme"] = form["theme"]
+        return redirect("/options")
     
-    @app.route("/options")
+    @app.route("/options", methods=["GET", "POST"])
     @login_required
     def options():
-        return render_template("options.html")
+        if request.method == "GET":
+            return render_template("options.html")
+        else:
+            return update_settings(request.form)
     
     @app.route("/kanji/<kanji>")
     def kanji_page(kanji: str):
@@ -78,9 +86,9 @@ def create_app(test_config=None):
 
     from . import lang
 
-    def use_english(text_id: str):
-        return lang.localize(text_id, lang.JAPANESE)
-    app.jinja_env.globals.update(localize=use_english)
+    # def use_english(text_id: str):
+    #     return lang.localize(text_id, lang.JAPANESE)
+    app.jinja_env.globals.update(localize=lang.localize)
     
 
     return app
\ No newline at end of file
diff --git a/kanken_online/lang.py b/kanken_online/lang.py
index 94bf30a..209a43d 100644
--- a/kanken_online/lang.py
+++ b/kanken_online/lang.py
@@ -1,3 +1,5 @@
+from flask import session
+
 EXISTING_STRINGS = {
     "kanken_online",
     "options",
@@ -47,6 +49,10 @@ ENGLISH = {
     "radical_index": "Radical index",
     "indivisible_index": "Indivisible kanji index",
     "phonetic_series": "Phonetic series",
+    "dark_theme": "Dark theme",
+    "light_theme": "Light theme",
+    "language": "Language",
+    "theme": "Color settings"
 }
 
 JAPANESE = {
@@ -74,17 +80,24 @@ JAPANESE = {
     "radical_index": "部首索引",
     "indivisible_index": "不可分漢字索引",
     "phonetic_series": "諧声域索引",
+    "dark_theme": "ダークモード",
+    "light_theme": "ライトモード",
+    "language": "言語",
+    "theme": "色設定"
 }
 
-LANGUAGES = [
-    ENGLISH,
-    JAPANESE
-]
+LANGUAGES = {
+    "en": ENGLISH,
+    "ja": JAPANESE
+}
 
 # assert all(all(key in lang for key in EXISTING_STRINGS) for lang in LANGUAGES)  # Ensure all strings are mapped for all existing languages
 # assert not [key for lang in LANGUAGES for key in lang if ((key in lang) and (key not in EXISTING_STRINGS))]
 # assert not any((((key in lang) and (key not in EXISTING_STRINGS)) for key in lang) for lang in LANGUAGES)  # Ensure no languages have strings not specified by the main index
 
 
-def localize(text_id: str, language: dict[str, str]) -> str:
+def localize(text_id: str, language: dict[str, str] = None) -> str:
+    if language is None:
+        preference = session.get("language", "en")
+        language = LANGUAGES.get(preference)
     return language[text_id]
diff --git a/kanken_online/templates/options.html b/kanken_online/templates/options.html
index 8350068..028b4e6 100644
--- a/kanken_online/templates/options.html
+++ b/kanken_online/templates/options.html
@@ -5,5 +5,19 @@
 {% endblock %}
 
 {% block content %}
-  Blahdy blah
+<form method="post">
+  <label for="language-select">{{ localize("language") }}</label>
+  <select name="language" id="language-select">
+    <option value="ja">日本語</option>
+    <option value="en">English</option>
+  </select>
+
+  <label for="theme-select">{{ localize("theme") }}</label>
+  <select name="theme" id="theme-select">
+    <option value="dark">{{ localize("dark_theme") }}</option>
+    <option value="light">{{ localize("light_theme") }}</option>
+  </select>
+  <hr>
+  <button type="submit">Okay</button>
+</form>
 {% endblock %}
\ No newline at end of file