diff --git a/Steepfile b/Steepfile
index eb09449d8..10c321185 100644
--- a/Steepfile
+++ b/Steepfile
@@ -8,8 +8,7 @@ target :lib do
     "lib/rbs/test.rb"
   )
 
-  library "pathname", "json", "logger", "monitor", "tsort", "uri", 'dbm', 'pstore', 'singleton', 'shellwords', 'fileutils', 'find', 'digest', 'abbrev', 'prettyprint'
-  signature 'stdlib/yaml/0'
+  library "pathname", "json", "logger", "monitor", "tsort", "uri", 'dbm', 'pstore', 'singleton', 'shellwords', 'fileutils', 'find', 'digest', 'abbrev', 'prettyprint', 'yaml'
   signature "stdlib/strscan/0/"
   signature "stdlib/optparse/0/"
   signature "stdlib/rdoc/0/"
diff --git a/lib/rbs/diff.rb b/lib/rbs/diff.rb
index deb46ac61..47a4d6d84 100644
--- a/lib/rbs/diff.rb
+++ b/lib/rbs/diff.rb
@@ -53,13 +53,13 @@ def build_methods(path)
         builder.build_instance(@type_name).methods
       rescue => e
         RBS.logger.warn("#{path}: (#{e.class}) #{e.message}")
-        {}
+        {} #: Hash[Symbol, Definition::Method]
       end
       singleton_methods = begin
         builder.build_singleton(@type_name).methods
       rescue => e
         RBS.logger.warn("#{path}: (#{e.class}) #{e.message}")
-        {}
+        {} #: Hash[Symbol, Definition::Method]
       end
 
       constant_children = begin
@@ -67,7 +67,7 @@ def build_methods(path)
         constant_resolver.children(@type_name)
       rescue => e
         RBS.logger.warn("#{path}: (#{e.class}) #{e.message}")
-        {}
+        {} #: Hash[Symbol, Constant]
       end
 
       [ instance_methods, singleton_methods, constant_children ]
@@ -101,7 +101,8 @@ def definition_method_to_s(key, kind, definition_method)
         prefix = kind == :instance ? "" : "self."
 
         if definition_method.alias_of
-          "alias #{prefix}#{key} #{prefix}#{definition_method.alias_of.defs.first.member.name}"
+          first_def = definition_method.alias_of.defs.first #: Definition::Method::TypeDef
+          "alias #{prefix}#{key} #{prefix}#{first_def.member.name}"
         else
           "def #{prefix}#{key}: #{definition_method.method_types.join(" | ")}"
         end
diff --git a/lib/rbs/prototype/runtime/value_object_generator.rb b/lib/rbs/prototype/runtime/value_object_generator.rb
index 975f772a7..8d89f0ebd 100644
--- a/lib/rbs/prototype/runtime/value_object_generator.rb
+++ b/lib/rbs/prototype/runtime/value_object_generator.rb
@@ -33,7 +33,9 @@ def build_decl
         # def self.members: () -> [ :foo, :bar ]
         # def members: () -> [ :foo, :bar ]
         def build_s_members
-          [:singleton, :instance].map do |kind|
+          (
+            [:singleton, :instance] #: Array[AST::Members::MethodDefinition::kind]
+          ).map do |kind|
             AST::Members::MethodDefinition.new(
               name: :members,
               overloads: [
diff --git a/sig/diff.rbs b/sig/diff.rbs
index 4f3b99269..ee11b205a 100644
--- a/sig/diff.rbs
+++ b/sig/diff.rbs
@@ -15,9 +15,12 @@ module RBS
     def each_diff: () { (String before, String after) -> void } -> void
 
     private def each_diff_by: (Symbol kind, Hash[::Symbol, Definition::Method] before_methods, Hash[::Symbol, Definition::Method] after_methods) { (String before, String after) -> void } -> void
-    private def build_methods: (Array[String] path) -> [ Hash[::Symbol, Definition::Method], Hash[::Symbol, Definition::Method] ]
+    private def build_methods: (Array[String] path) -> [ Hash[::Symbol, Definition::Method], Hash[::Symbol, Definition::Method] , Hash[Symbol, Constant]]
     private def build_env: (Array[String] path) -> Environment
     private def build_builder: (Environment env) -> DefinitionBuilder
     private def definition_method_to_s: (Symbol key, Symbol kind, Definition::Method definition_method) -> String?
+    private def each_diff_methods: (Symbol kind, Hash[Symbol, Definition::Method], Hash[Symbol, Definition::Method]) { (String before, String after) -> void } -> void
+    private def each_diff_constants: (Hash[Symbol, Constant] before_constants, Hash[Symbol, Constant] after_constants) { (String before, String after) -> void } -> void
+    private def constant_to_s: (Constant?) -> String
   end
 end
diff --git a/sig/prototype/runtime.rbs b/sig/prototype/runtime.rbs
index 5866ea4be..0221518be 100644
--- a/sig/prototype/runtime.rbs
+++ b/sig/prototype/runtime.rbs
@@ -2,12 +2,17 @@ module RBS
   module Prototype
     class Runtime
       module Reflection
+        self.@object_class: UnboundMethod
         def self.object_class: (Module value) -> Class
 
+        self.@constants_of: UnboundMethod
         def self.constants_of: (Module mod, ?bool inherit) -> Array[Symbol]
       end
 
       module Helpers
+        @module_name_method: UnboundMethod
+        @untyped: Types::Bases::Any
+
         private
 
         def const_name: (Module const) -> String?
@@ -19,12 +24,15 @@ module RBS
 
         def to_type_name: (String name, ?full_name: bool) -> TypeName
 
-        def untyped: () -> untyped
+        def untyped: () -> Types::Bases::Any
       end
 
       class ValueObjectBase
         include Helpers
 
+        # @target_class stores the singleton object of `Data` or `Struct` subclass
+        @target_class: untyped
+
         def build_decl: () -> AST::Declarations::Class
 
         private
@@ -33,6 +41,10 @@ module RBS
 
         def build_s_members: () -> Array[AST::Members::MethodDefinition]
 
+        def build_super_class: () -> AST::Declarations::Class::Super
+
+        def add_decl_members: (AST::Declarations::Class) -> void
+
         def initialize: (Class target_class) -> void
       end
 
@@ -77,9 +89,9 @@ module RBS
 
         def skip_mixin?: (type_name: TypeName, module_name: TypeName, mixin_class: mixin_class) -> bool
 
-        def skip_singleton_method?: (module_name: TypeName, name: Symbol) -> bool
+        def skip_singleton_method?: (module_name: TypeName, method: UnboundMethod, accessibility: Definition::accessibility) -> bool
 
-        def skip_instance_method?: (module_name: TypeName, name: Symbol) -> bool
+        def skip_instance_method?: (module_name: TypeName, method: UnboundMethod, accessibility: Definition::accessibility) -> bool
 
         def skip_constant?: (module_name: String, name: Symbol) -> bool
 
@@ -147,6 +159,8 @@ module RBS
 
       def generate_module: (Module mod) -> void
 
+      def generate_mixin: (Module mod, AST::Declarations::Class | AST::Declarations::Module, TypeName, TypeName) -> void
+
       # Generate/find outer module declarations
       # This is broken down into another method to comply with `DRY`
       # This generates/finds declarations in nested form & returns the last array of declarations
@@ -158,6 +172,8 @@ module RBS
 
       def block_from_ast_of: (UnboundMethod method) -> Types::Block?
 
+      def block_from_body: (RubyVM::AbstractSyntaxTree::Node) -> Types::Block?
+
       def can_alias?: (Module, UnboundMethod) -> bool
 
       def type_params: (Module) -> Array[AST::TypeParam]
diff --git a/steep/Gemfile b/steep/Gemfile
index d09c409ca..0956766fd 100644
--- a/steep/Gemfile
+++ b/steep/Gemfile
@@ -1,4 +1,4 @@
 source "https://rubygems.org"
 
-gem "rbs", "~> 3.2.2"
-gem "steep", "~> 1.6.0"
+gem "rbs"
+gem "steep"
diff --git a/steep/Gemfile.lock b/steep/Gemfile.lock
index 9dca27ab5..fd4ecdc65 100644
--- a/steep/Gemfile.lock
+++ b/steep/Gemfile.lock
@@ -1,6 +1,7 @@
 GEM
   remote: https://rubygems.org/
   specs:
+    abbrev (0.1.1)
     activesupport (7.1.1)
       base64
       bigdecimal
@@ -39,7 +40,8 @@ GEM
     rb-fsevent (0.11.2)
     rb-inotify (0.10.1)
       ffi (~> 1.0)
-    rbs (3.2.2)
+    rbs (3.3.0)
+      abbrev
     ruby2_keywords (0.0.5)
     securerandom (0.3.0)
     steep (1.6.0)
@@ -68,8 +70,8 @@ PLATFORMS
   ruby
 
 DEPENDENCIES
-  rbs (~> 3.2.2)
-  steep (~> 1.6.0)
+  rbs
+  steep
 
 BUNDLED WITH
    2.4.18
diff --git a/test/rbs/cli_test.rb b/test/rbs/cli_test.rb
index b35ff3b08..cde84b345 100644
--- a/test/rbs/cli_test.rb
+++ b/test/rbs/cli_test.rb
@@ -15,7 +15,17 @@ def stderr
     @stderr ||= StringIO.new
   end
 
-  def run_rbs(*commands, bundler: true)
+  # Run `rbs collection` with fresh bundler environment
+  #
+  # You need this method to test `rbs collection` features.
+  # `rbs collection` loads gems from Bundler context, so re-using the currenr Bundler context (used to develop rbs gem) causes issues.
+  #
+  # - If `bundler: true` is given, it runs `rbs collection` command with `bundle exec`
+  # - If `bundler: false` is given, it runs `rbs collection` command without `bundle exec`
+  #
+  # We cannot run tests that uses this method in ruby CI.
+  #
+  def run_rbs_collection(*commands, bundler:)
     stdout, stderr, status =
       Bundler.with_unbundled_env do
         bundle_exec = []
@@ -26,7 +36,7 @@ def run_rbs(*commands, bundler: true)
           rbs_path << (":" + rblib)
         end
 
-        Open3.capture3({ "RUBYLIB" => rbs_path }, *bundle_exec, "#{__dir__}/../../exe/rbs", *commands, chdir: Dir.pwd)
+        Open3.capture3({ "RUBYLIB" => rbs_path }, *bundle_exec, "#{__dir__}/../../exe/rbs", "collection", *commands, chdir: Dir.pwd)
       end
 
     if block_given?
@@ -849,7 +859,7 @@ def test_collection_install
              2.2.0
         LOCK
 
-        _stdout, _stderr = run_rbs("collection", "install")
+        _stdout, _stderr = run_rbs_collection("install", bundler: true)
 
         rbs_collection_lock = dir.join('rbs_collection.lock.yaml')
         assert rbs_collection_lock.exist?
@@ -861,7 +871,7 @@ def test_collection_install
 
         Dir.mkdir("child")
         Dir.chdir("child") do
-          _stdout, _stderr = run_rbs("collection", "install")
+          _stdout, _stderr = run_rbs_collection("install", bundler: true)
           assert rbs_collection_lock.exist?
           assert collection_dir.exist?
         end
@@ -891,7 +901,7 @@ def test_collection_install_frozen
         YAML
         dir.join('rbs_collection.lock.yaml').write(lock_content)
 
-        run_rbs("collection", "install", "--frozen", bundler: false)
+        run_rbs_collection("install", "--frozen", bundler: false)
 
         refute dir.join(RBS::Collection::Config::PATH).exist?
         assert dir.join('gem_rbs_collection/ast').exist?
@@ -933,7 +943,7 @@ def test_collection_update
              2.2.0
         LOCK
 
-        run_rbs("collection", "update", bundler: true)
+        run_rbs_collection("update", bundler: true)
 
         assert dir.join('rbs_collection.lock.yaml').exist?
         assert dir.join('gem_rbs_collection/ast').exist?
@@ -997,7 +1007,7 @@ def test_collection_install_gemspec
         RUBY
         (dir/"sig").mkdir
 
-        stdout, _ = run_rbs("collection", "install", bundler: true)
+        stdout, _ = run_rbs_collection("install", bundler: true)
 
         assert_match(/Installing ast:(\d(\.\d)*)/, stdout)
         refute_match(/^Using hola:(\d(\.\d)*)/, stdout)
@@ -1027,15 +1037,17 @@ def x: () -> untyped
         end
       RBS
 
-      stdout, stderr = run_rbs('subtract', minuend.to_s, subtrahend.to_s)
-      assert_empty stderr
-      assert_equal <<~RBS, stdout
-        use A::B
+      with_cli do |cli|
+        cli.run(['subtract', minuend.to_s, subtrahend.to_s])
+        assert_empty stderr.string
+        assert_equal <<~RBS, stdout.string
+          use A::B
 
-        class C
-          def y: () -> untyped
-        end
-      RBS
+          class C
+            def y: () -> untyped
+          end
+        RBS
+      end
     end
   end
 
@@ -1065,15 +1077,17 @@ def y: () -> untyped
         end
       RBS
 
-      stdout, stderr = run_rbs('subtract', minuend.to_s, '--subtrahend', subtrahend_1.to_s, '--subtrahend', subtrahend_2.to_s)
-      assert_empty stderr
-      assert_equal <<~RBS, stdout
-        use A::B
+      with_cli do |cli|
+        cli.run(['subtract', minuend.to_s, '--subtrahend', subtrahend_1.to_s, '--subtrahend', subtrahend_2.to_s])
+        assert_empty stderr.string
+        assert_equal <<~RBS, stdout.string
+          use A::B
 
-        class C
-          def z: () -> untyped
-        end
-      RBS
+          class C
+            def z: () -> untyped
+          end
+        RBS
+      end
     end
   end
 
@@ -1096,16 +1110,18 @@ def x: () -> untyped
         end
       RBS
 
-      stdout, stderr = run_rbs('subtract', '--write', minuend.to_s, subtrahend.to_s)
-      assert_empty stderr
-      assert_empty stdout
-      assert_equal minuend.read, <<~RBS
-        use A::B
-
-        class C
-          def y: () -> untyped
-        end
-      RBS
+      with_cli do |cli|
+        cli.run(['subtract', '--write', minuend.to_s, subtrahend.to_s])
+        assert_empty stderr.string
+        assert_empty stdout.string
+        assert_equal minuend.read, <<~RBS
+          use A::B
+
+          class C
+            def y: () -> untyped
+          end
+        RBS
+      end
     end
   end
 
@@ -1127,10 +1143,12 @@ def x: () -> untyped
         end
       RBS
 
-      stdout, stderr = run_rbs('subtract', '--write', minuend.to_s, subtrahend.to_s)
-      assert_empty stderr
-      assert_empty stdout
-      assert_equal minuend.exist?, false
+      with_cli do |cli|
+        cli.run(['subtract', '--write', minuend.to_s, subtrahend.to_s])
+        assert_empty stderr.string
+        assert_empty stdout.string
+        refute_predicate minuend, :exist?
+    end
     end
   end
 
@@ -1181,36 +1199,40 @@ class Foo
 
   def test_diff_markdown
     mktmp_diff_case do |dir1, dir2|
-      stdout, stderr = run_rbs('diff', '--format', 'markdown', '--type-name', 'Foo', '--before', dir1.to_s, '--after', dir2.to_s)
-
-      assert_equal <<~MARKDOWN, stdout
-        | before | after |
-        | --- | --- |
-        | `def qux: (untyped) -> untyped` | `-` |
-        | `def quux: () -> void` | `alias quux bar` |
-        | `def self.baz: () -> (::Integer \\| ::String)` | `def self.baz: (::Integer) -> ::Integer?` |
-        | `CONST: ::Array[::Integer]` | `CONST: ::Array[::String]` |
-      MARKDOWN
+      with_cli do |cli|
+        cli.run(['diff', '--format', 'markdown', '--type-name', 'Foo', '--before', dir1.to_s, '--after', dir2.to_s])
+
+        assert_equal <<~MARKDOWN, stdout.string
+          | before | after |
+          | --- | --- |
+          | `def qux: (untyped) -> untyped` | `-` |
+          | `def quux: () -> void` | `alias quux bar` |
+          | `def self.baz: () -> (::Integer \\| ::String)` | `def self.baz: (::Integer) -> ::Integer?` |
+          | `CONST: ::Array[::Integer]` | `CONST: ::Array[::String]` |
+        MARKDOWN
+      end
     end
   end
 
   def test_diff_diff
     mktmp_diff_case do |dir1, dir2|
-      stdout, stderr = run_rbs('diff', '--format', 'diff', '--type-name', 'Foo', '--before', dir1.to_s, '--after', dir2.to_s)
+      with_cli do |cli|
+        cli.run(['diff', '--format', 'diff', '--type-name', 'Foo', '--before', dir1.to_s, '--after', dir2.to_s])
 
-      assert_equal <<~DIFF, stdout
-        - def qux: (untyped) -> untyped
-        + -
+        assert_equal <<~DIFF, stdout.string
+          - def qux: (untyped) -> untyped
+          + -
 
-        - def quux: () -> void
-        + alias quux bar
+          - def quux: () -> void
+          + alias quux bar
 
-        - def self.baz: () -> (::Integer | ::String)
-        + def self.baz: (::Integer) -> ::Integer?
+          - def self.baz: () -> (::Integer | ::String)
+          + def self.baz: (::Integer) -> ::Integer?
 
-        - CONST: ::Array[::Integer]
-        + CONST: ::Array[::String]
-      DIFF
+          - CONST: ::Array[::Integer]
+          + CONST: ::Array[::String]
+        DIFF
+      end
     end
   end
 end