diff --git a/Gemfile b/Gemfile
index 36783f0d..e2d74068 100644
--- a/Gemfile
+++ b/Gemfile
@@ -24,7 +24,6 @@ gem 'hexapdf'
 gem 'jwt', require: false
 gem 'lograge'
 gem 'numo-narray-alt', require: false
-gem 'oj'
 gem 'onnxruntime', require: false
 gem 'pagy'
 gem 'pg', require: false
diff --git a/Gemfile.lock b/Gemfile.lock
index 933cf9a8..d72a8bd7 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -271,7 +271,7 @@ GEM
       rdoc (>= 4.0.0)
       reline (>= 0.4.2)
     jmespath (1.6.2)
-    json (2.19.7)
+    json (2.19.8)
     jwt (3.2.0)
       base64
     language_server-protocol (3.17.0.5)
@@ -334,9 +334,6 @@ GEM
     nokogiri (1.19.3-x86_64-linux-musl)
       racc (~> 1.4)
     numo-narray-alt (0.10.3)
-    oj (3.16.16)
-      bigdecimal (>= 3.0)
-      ostruct (>= 0.2)
     onnxruntime (0.10.1-aarch64-linux)
       ffi
     onnxruntime (0.10.1-arm64-darwin)
@@ -346,7 +343,6 @@ GEM
     openssl (4.0.1)
     orm_adapter (0.5.0)
     os (1.1.4)
-    ostruct (0.6.3)
     package_json (0.2.0)
     pagy (43.4.4)
       json
@@ -623,7 +619,6 @@ DEPENDENCIES
   letter_opener_web
   lograge
   numo-narray-alt
-  oj
   onnxruntime
   pagy
   pg
diff --git a/config/initializers/oj.rb b/config/initializers/oj.rb
deleted file mode 100644
index 5f609ded..00000000
--- a/config/initializers/oj.rb
+++ /dev/null
@@ -1,3 +0,0 @@
-# frozen_string_literal: true
-
-Oj.optimize_rails