diff --git a/lib/tzinfo/amagi.rb b/lib/tzinfo/amagi.rb
new file mode 100644
index 00000000..f292b841
--- /dev/null
+++ b/lib/tzinfo/amagi.rb
@@ -0,0 +1,5 @@
+# Top level module for TZInfo.
+module TZInfo
+  module Amagi
+  end
+end
diff --git a/lib/tzinfo/amagi/definition/Amagi.rb b/lib/tzinfo/amagi/definition/Amagi.rb
new file mode 100644
index 00000000..eeb9cea7
--- /dev/null
+++ b/lib/tzinfo/amagi/definition/Amagi.rb
@@ -0,0 +1,36 @@
+module TZInfo
+  module Amagi
+    module Definition
+      module Amagi
+
+        DEFAULT_SWITCH_OVER_EPOCH = "08:30:00"
+
+        include TimezoneDefinition
+        switch_timezone = ENV["AMAGI_DST_SWITCH_TO"]
+        dst_switch_time = ENV["AMAGI_DST_SWITCH_TIME"]
+        parsed_date_time = DateTime.strptime(dst_switch_time, "%Y-%m-%dT%H:%M:%S") if dst_switch_time
+        d  = dst_switch_time ? parsed_date_time.to_date : Date.current
+        switch_at_time = dst_switch_time ? parsed_date_time.strftime("%H:%M:%S") : DEFAULT_SWITCH_OVER_EPOCH
+        switch_over_epoch = Time.find_zone("UTC").parse(d.strftime("%Y-%m-%d") + " " + switch_at_time ).to_i
+        if switch_timezone == "AST"
+          timezone 'Amagi' do |tz|
+            tz.offset :o0, 23400, 0, :ADST
+            tz.offset :o1, 19800, 0, :AST
+
+            tz.transition d.year, d.month, :o1, switch_over_epoch
+
+          end
+        elsif switch_timezone == "ADST"
+          timezone 'Amagi' do |tz|
+            tz.offset :o0, 19800, 0, :AST
+            tz.offset :o1, 23400, 0, :ADST
+
+            tz.transition d.year, d.month, :o1, switch_over_epoch
+
+          end
+        end
+
+      end
+    end
+  end
+end
diff --git a/lib/tzinfo/amagi/timezone.rb b/lib/tzinfo/amagi/timezone.rb
new file mode 100644
index 00000000..de1afd64
--- /dev/null
+++ b/lib/tzinfo/amagi/timezone.rb
@@ -0,0 +1,8 @@
+module TZInfo
+  module Amagi
+    module Timezone
+      include TimezoneIndexDefinition
+      timezone 'Amagi'
+    end
+  end
+end
diff --git a/lib/tzinfo/data_sources/ruby_data_source.rb b/lib/tzinfo/data_sources/ruby_data_source.rb
index 41c384a4..e836ae27 100644
--- a/lib/tzinfo/data_sources/ruby_data_source.rb
+++ b/lib/tzinfo/data_sources/ruby_data_source.rb
@@ -54,10 +54,19 @@ def initialize
           end
         end
 
+        data_file_amagi = File.join('', 'tzinfo', 'amagi.rb')
+        path_amagi = $".reverse_each.detect {|p| p.end_with?(data_file_amagi) }
+        if path_amagi
+          @base_path_amagi_timezone = RubyCoreSupport.untaint(File.join(File.dirname(path_amagi), 'amagi' ))
+        else
+          @base_path_amagi_timezone = 'tzinfo/amagi'
+        end
+
         require_index('timezones')
         require_index('countries')
+        require_data_amagi('timezone')
 
-        @data_timezone_identifiers = Data::Indexes::Timezones.data_timezones
+        @data_timezone_identifiers = Data::Indexes::Timezones.data_timezones + Amagi::Timezone.data_timezones
         @linked_timezone_identifiers = Data::Indexes::Timezones.linked_timezones
         @countries = Data::Indexes::Countries.countries
         @country_codes = @countries.keys.sort!.freeze
@@ -90,11 +99,18 @@ def load_timezone_info(identifier)
         split_identifier = valid_identifier.gsub(/-/, '__m__').gsub(/\+/, '__p__').split('/')
 
         begin
-          require_definition(split_identifier)
+          if split_identifier == ["Amagi"]
+            require_definition_amagi("Amagi")
+            n = Amagi::Definition
+            split_identifier.each {|part| n = n.const_get(part) }
+            n.get
+          else
+            require_definition(split_identifier)
+            m = Data::Definitions
 
-          m = Data::Definitions
-          split_identifier.each {|part| m = m.const_get(part) }
-          m.get
+            split_identifier.each {|part| m = m.const_get(part) }
+            m.get
+          end
         rescue LoadError, NameError => e
           raise InvalidTimezoneIdentifier, "#{e.message.encode(Encoding::UTF_8)} (loading #{valid_identifier})"
         end
@@ -115,6 +131,10 @@ def require_definition(identifier)
         require_data('definitions', *identifier)
       end
 
+      def require_definition_amagi(identifier)
+        require_data_amagi('defintion', *identifier)
+      end
+
       # Requires an index by its name.
       #
       # @param name [String] an index name.
@@ -129,6 +149,10 @@ def require_data(*file)
         require(File.join(@base_path, *file))
       end
 
+      def require_data_amagi(*file)
+        require(File.join(@base_path_amagi_timezone, *file))
+      end
+
       # @return [String] a `String` containing TZInfo::Data version infomation
       #   for inclusion in the #to_s and #inspect output.
       def version_info
diff --git a/lib/tzinfo/format1/timezone_index_definition.rb b/lib/tzinfo/format1/timezone_index_definition.rb
index 5d4518aa..69bc3294 100644
--- a/lib/tzinfo/format1/timezone_index_definition.rb
+++ b/lib/tzinfo/format1/timezone_index_definition.rb
@@ -31,7 +31,7 @@ module ClassMethods #:nodoc:
         #   `String#<=>`.
         def data_timezones
           unless @data_timezones.frozen?
-            @data_timezones = @data_timezones.sort.freeze
+            @data_timezones = @data_timezones.sort
           end
           @data_timezones
         end