diff --git a/backend/app/controllers/wiki_pages_controller.rb b/backend/app/controllers/wiki_pages_controller.rb
index 9a0c310..3973e48 100644
--- a/backend/app/controllers/wiki_pages_controller.rb
+++ b/backend/app/controllers/wiki_pages_controller.rb
@@ -2,124 +2,29 @@ class WikiPagesController < ApplicationController
   rescue_from Wiki::Commit::Conflict, with: :render_wiki_conflict
 
   def index
-    # 互換性のための化石リソース
-    # TODO: ヘルプおよびタグ・グループ追加後に，
-    # TODO: タグ説明とヘルプ、タグ・グループから取得する作りに変更する．
-
     title = params[:title].to_s.strip
-    if title.blank?
-      tag_descriptions = TagDescription.where(language_code: :ja).map do |td|
-        { id: td.id,
-          tag_name_id: td.tag.tag_name(:ja).id,
-          body: td.body,
-          created_user_id: td.created_by_user_id,
-          updated_user_id: td.updated_by_user_id,
-          created_at: td.created_at,
-          updated_at: td.updated_at,
-          discarded_at: nil,
-          version_no: td.version_no,
-          title: td.tag.name(:ja),
-          deprecated_at: td.tag.deprecated_at }
-      end
-      # TODO: ヘルプ移行したらここに追記
-      # TODO: タグ・グループ追加したらここに追記
+    descriptions = TagDescription.where(language_code: 'ja')
+        .includes(tag: :tag_names)
+    pages = unmigrated_wiki_pages.includes(tag_name: :tag)
 
-      # TODO: ヘルプ、タグ・グループ移行したらそれらもタイトルから除外に含める．
-      # てかこれ何順?
-      wiki_pages =
-          WikiPageRepr.base(WikiPage.joins(:tag_name).includes(tag_name: :tag))
-          .reject { |wp| tag_descriptions.any? { |td| td.title == wp.title } }
-
-      json = tag_descriptions + wiki_pages
-
-      return render json:
+    if title.present?
+      pattern = "%#{ ApplicationRecord.sanitize_sql_like(title) }%"
+      descriptions = descriptions.joins(tag: :tag_names)
+          .where(tag_names: { language_code: 'ja', primary_flg: true })
+          .where('tag_names.name LIKE ?', pattern).limit(20)
+      pages = pages.where('tag_names.name LIKE ?', pattern).limit(20)
     end
 
-    q =
-        TagDescription.joins(tag: :tag_names)
-        .where(language_code: :ja)
-        .where(tag: { tag_names: { language_code: :ja, primary_flg: true } })
-        .where('tag_names.name LIKE ?', "%#{ ApplicationRecord.sanitize_sql_like(title) }%")
-    tag_descriptions = q.limit(20).map do |td|
-      { id: td.id,
-        tag_name_id: td.tag.tag_name(:ja).id,
-        body: td.body,
-        created_user_id: td.created_by_user_id,
-        updated_user_id: td.updated_by_user_id,
-        created_at: td.created_at,
-        updated_at: td.updated_at,
-        discarded_at: nil,
-        version_no: td.version_no,
-        title: td.tag.name(:ja),
-        deprecated_at: td.tag.deprecated_at }
-    end
-
-    q =
-        WikiPage.joins(:tag_name).includes(tag_name: :tag)
-        .where('tag_names.name LIKE ?', "%#{ WikiPage.sanitize_sql_like(title) }%")
-    # TODO: ヘルプ、タグ・グループ移行したらそれらもタイトルから除外に含める．
-    wiki_pages =
-        WikiPageRepr.base(q.limit(20))
-        .reject { |wp| tag_descriptions.any? { |td| td.title == wp.title } }
-
-    json = (tag_descriptions + wiki_pages)[...20]
-
+    json = descriptions.map { |description| WikiPageRepr.tag_description(description) }
+    json.concat(WikiPageRepr.base(pages))
+    json = json.first(20) if title.present?
     render json:
   end
 
   def show
     tag_description = TagDescription.find_by(id: params[:id])
 
-    if tag_description
-      rev =
-          if params[:version].present?
-            TagDescriptionVersion.find_by(id: params[:version])
-          else
-            TagDescriptionVersion.find_by(tag_id: tag_description.tag_id,
-                                          language_code: :ja,
-                                          version_no: tag_description.version_no)
-          end
-
-      if rev
-        body =
-            if rev.version_no == tag_description.version_no
-              tag_description.body
-            else
-              rev.body
-            end
-        revision_id = rev.id
-        pred = TagDescriptionVersion.find_by(tag_id: tag_description.tag_id,
-                                             language_code: :ja,
-                                             version_no: tag_description.version_no - 1)&.id
-        succ = TagDescriptionVersion.find_by(tag_id: tag_description.tag_id,
-                                             language_code: :ja,
-                                             version_no: tag_description.version_no + 1)&.id
-        updated_at =
-            if rev.version_no == tag_description.version_no
-              tag_description.updated_at
-            else
-              rev.created_at
-            end
-
-        json = 
-            { id: tag_description.id,
-              tag_name_id: tag_description.tag.tag_name(:ja).id,
-              body:,
-              created_user_id: tag_description.created_by_user_id,
-              updated_user_id: tag_description.updated_by_user_id,
-              created_at: tag_description.created_at,
-              updated_at:,
-              discarded_at: nil,
-              version_no: tag_description.version_no,
-              title: tag_description.tag.name(:ja),
-              deprecated_at: tag_description.tag.deprecated_at,
-              revision_id:,
-              pred:,
-              succ: }
-
-        return render json:
-      end
-    end
+    return render_wiki_page_by_tag_description tag_description if tag_description
 
     page = WikiPage.joins(:tag_name)
                    .includes(tag_name: :tag)
@@ -130,27 +35,30 @@ class WikiPagesController < ApplicationController
 
   def show_by_title
     title = params[:title].to_s.strip
+
+    tag_description = tag_description_by_title(title)
+
+    return render_wiki_page_by_tag_description tag_description if tag_description
+
     page = WikiPage.joins(:tag_name)
                    .includes(tag_name: :tag)
                    .find_by(tag_name: { name: title })
+
     render_wiki_page_or_404 page
   end
 
   def exists
-    if WikiPage.exists?(id: params[:id])
-      head :no_content
-    else
-      head :not_found
-    end
+    return head :no_content if TagDescription.exists?(id: params[:id])
+
+    head WikiPage.exists?(id: params[:id]) ? :no_content : :not_found
   end
 
   def exists_by_title
     title = params[:title].to_s.strip
-    if WikiPage.joins(:tag_name).exists?(tag_names: { name: title })
-      head :no_content
-    else
-      head :not_found
-    end
+    return head :no_content if tag_description_by_title(title)
+
+    exists = WikiPage.joins(:tag_name).exists?(tag_names: { name: title })
+    head exists ? :no_content : :not_found
   end
 
   def diff
@@ -160,12 +68,20 @@ class WikiPagesController < ApplicationController
     from = params[:from].presence
     to = params[:to].presence
 
-    page = WikiPage.joins(:tag_name).includes(tag_name: :tag).find(id)
-
-    from_rev = from && page.wiki_revisions.find(from)
-    to_rev = to ? page.wiki_revisions.find(to) : page.current_revision
-    if ((from_rev && !(from_rev.content?)) || !(to_rev&.content?))
-      return render_unprocessable_entity('差分を表示できない版です．')
+    description = TagDescription.find_by(id:)
+    if description
+      versions = description_versions(description)
+      from_rev = from && versions.find(from)
+      to_rev = to ? versions.find(to) : versions.find_by!(version_no: description.version_no)
+      resource = WikiPageRepr.tag_description(description)
+    else
+      page = WikiPage.joins(:tag_name).includes(tag_name: :tag).find(id)
+      from_rev = from && page.wiki_revisions.find(from)
+      to_rev = to ? page.wiki_revisions.find(to) : page.current_revision
+      if ((from_rev && !from_rev.content?) || !to_rev&.content?)
+        return render_unprocessable_entity('差分を表示できない版です．')
+      end
+      resource = WikiPageRepr.base(page)
     end
 
     diffs = Diff::LCS.sdiff(from_rev&.body&.lines || [], to_rev.body.lines)
@@ -183,9 +99,9 @@ class WikiPagesController < ApplicationController
       end
     }.flatten.compact
 
-    render json: { wiki_page_id:      page.id,
-                   title:             page.title,
-                   deprecated_at:     page.deprecated_at,
+    render json: { wiki_page_id:      resource.fetch('id'),
+                   title:             resource.fetch('title'),
+                   deprecated_at:     resource.fetch('deprecated_at'),
                    older_revision_id: from_rev&.id,
                    newer_revision_id: to_rev.id,
                    diff:              diff_json }
@@ -202,18 +118,16 @@ class WikiPagesController < ApplicationController
     return render_unprocessable_entity('タイトルは必須です．', field: :title) if title.blank?
     return render_unprocessable_entity('本文は必須です．', field: :body) if body.blank?
 
-    tag_name = TagName.find_or_create_by!(language_code: 'ja', name: title) do |name|
-      name.script_code = 'Jpan'
-      name.primary_flg = true
-      name.auto_generated = false
-    end
+    page = ApplicationRecord.transaction do
+      tag_name = TagName.find_or_create_by!(language_code: 'ja', name: title) do |name|
+        name.script_code = 'Jpan'
+        name.primary_flg = true
+        name.auto_generated = false
+      end
 
-    page =
-        Wiki::Commit.create_content!(
-            tag_name:,
-            body:,
-            created_by_user: current_user,
-            message:)
+      Wiki::Commit.create_content!(
+          tag_name:, body:, created_by_user: current_user, message:)
+    end
 
     render json: WikiPageRepr.base(page), status: :created
   rescue ActiveRecord::RecordInvalid => e
@@ -240,7 +154,7 @@ class WikiPagesController < ApplicationController
 
       old_title = page.title
 
-      tag = Tag.find_by(tag_name_id: page.tag_name_id)
+      tag = page.tag_name.tag
 
       if tag && title != old_title
         TagVersioning.ensure_snapshot!(tag, created_by_user: current_user)
@@ -266,23 +180,33 @@ class WikiPagesController < ApplicationController
 
   def changes
     id = params[:id].presence
-    q = WikiRevision.joins(wiki_page: :tag_name)
-                    .includes(:created_user, wiki_page: { tag_name: :tag })
-                    .order(id: :desc)
-    q = q.where(wiki_page_id: id) if id
+    description = id && TagDescription.find_by(id:)
+    if description
+      return render json: description_changes(TagDescription.where(id: description.id))
+    end
 
-    render json: q.limit(200).map { |rev|
-      { revision_id:  rev.id,
-        pred:         rev.base_revision_id,
-        succ:         nil,
-        wiki_page:    { id: rev.wiki_page_id,
-                        title: rev.wiki_page.title,
-                        deprecated_at: rev.wiki_page.deprecated_at },
-        user:         rev.created_user && { id: rev.created_user.id, name: rev.created_user.name },
-        kind:         rev.kind,
-        message:      rev.message,
-        timestamp:    rev.created_at }
-    }.compact
+    pages = id ? WikiPage.where(id:) : unmigrated_wiki_pages
+    revisions = WikiRevision.joins(wiki_page: :tag_name)
+        .where(wiki_page_id: pages.select(:id))
+        .includes(:created_user, wiki_page: { tag_name: :tag })
+        .order(id: :desc).limit(200)
+    json = revisions.map { |rev|
+      { revision_id: rev.id,
+        pred: rev.base_revision_id,
+        succ: nil,
+        wiki_page: { id: rev.wiki_page_id,
+                     title: rev.wiki_page.title,
+                     deprecated_at: rev.wiki_page.deprecated_at },
+        user: rev.created_user && { id: rev.created_user.id, name: rev.created_user.name },
+        kind: rev.kind,
+        message: rev.message,
+        timestamp: rev.created_at }
+    }
+    unless id
+      json.concat(description_changes(TagDescription.where(language_code: 'ja')))
+      json.sort_by! { |row| -row[:revision_id] }
+    end
+    render json: json.first(200)
   end
 
   private
@@ -308,6 +232,67 @@ class WikiPagesController < ApplicationController
     render json: WikiPageRepr.base(page).merge(body:, revision_id:, pred:, succ:, updated_at:)
   end
 
+  def render_wiki_page_by_tag_description description
+    versions = description_versions(description)
+    historical = params[:version].present?
+    rev = historical ? versions.find_by(id: params[:version]) :
+        versions.find_by(version_no: description.version_no)
+    return head :not_found unless rev
+
+    pred = versions.find_by(version_no: rev.version_no - 1)&.id
+    succ = versions.find_by(version_no: rev.version_no + 1)&.id
+    body = historical ? rev.body : description.body
+    updated_at = historical ? rev.created_at : description.updated_at
+    render json: WikiPageRepr.tag_description(description).merge(
+        body:, revision_id: rev.id, pred:, succ:, updated_at:)
+  end
+
+  def description_versions description
+    TagDescriptionVersion.where(tag_id: description.tag_id,
+                                language_code: description.language_code)
+  end
+
+  def tag_description_by_title title
+    TagDescription.joins(tag: :tag_names)
+        .find_by(language_code: 'ja', tag_names: { language_code: 'ja', name: title })
+  end
+
+  def unmigrated_wiki_pages
+    descriptions = TagDescription.where(language_code: 'ja')
+    WikiPage.joins(:tag_name).where.not(id: descriptions.select(:id))
+        .where('tag_names.tag_id IS NULL OR tag_names.tag_id NOT IN (?)',
+               descriptions.select(:tag_id))
+  end
+
+  def description_changes descriptions
+    versions = TagDescriptionVersion.where(language_code: 'ja',
+                                           tag_id: descriptions.select(:tag_id))
+        .order(id: :desc).limit(200).to_a
+    return [] if versions.empty?
+
+    by_tag = descriptions.where(tag_id: versions.map(&:tag_id))
+        .includes(tag: :tag_names).index_by(&:tag_id)
+    users = User.where(id: versions.map(&:created_by_user_id)).index_by(&:id)
+    predecessors = TagDescriptionVersion.where(
+        language_code: 'ja', tag_id: by_tag.keys,
+        version_no: versions.map { |version| version.version_no - 1 })
+        .pluck(:tag_id, :version_no, :id)
+        .to_h { |tag_id, version_no, id| [[tag_id, version_no], id] }
+    versions.map do |version|
+      description = by_tag.fetch(version.tag_id)
+      user = users[version.created_by_user_id]
+      { revision_id: version.id,
+        pred: predecessors[[version.tag_id, version.version_no - 1]],
+        succ: nil,
+        wiki_page: { id: description.id, title: description.tag.name('ja'),
+                     deprecated_at: description.tag.deprecated_at },
+        user: user && { id: user.id, name: user.name },
+        kind: 'content',
+        message: nil,
+        timestamp: version.created_at }
+    end
+  end
+
   def find_revision page
     if params[:version].present?
       page.wiki_revisions.find_by(id: params[:version])
diff --git a/backend/app/representations/wiki_page_repr.rb b/backend/app/representations/wiki_page_repr.rb
index ee09de3..a217341 100644
--- a/backend/app/representations/wiki_page_repr.rb
+++ b/backend/app/representations/wiki_page_repr.rb
@@ -10,6 +10,21 @@ module WikiPageRepr
     wiki_page.as_json(BASE)
   end
 
+  def tag_description description
+    tag = description.tag
+    { 'id' => description.id,
+      'tag_name_id' => tag.tag_name('ja')&.id,
+      'body' => description.body,
+      'created_user_id' => description.created_by_user_id,
+      'updated_user_id' => description.updated_by_user_id,
+      'created_at' => description.created_at,
+      'updated_at' => description.updated_at,
+      'discarded_at' => nil,
+      'version_no' => description.version_no,
+      'title' => tag.name('ja'),
+      'deprecated_at' => tag.deprecated_at }
+  end
+
   def many wiki_pages
     wiki_pages.map { |p| base(p) }
   end
diff --git a/backend/app/services/wiki/commit.rb b/backend/app/services/wiki/commit.rb
index bd6fb7b..14afa7b 100644
--- a/backend/app/services/wiki/commit.rb
+++ b/backend/app/services/wiki/commit.rb
@@ -57,9 +57,6 @@ module Wiki
       line_shas = lines.map { |line| Digest::SHA256.hexdigest(line) }
       tree_sha = Digest::SHA256.hexdigest(line_shas.join(','))
 
-      line_id_by_sha = upsert_lines!(lines, line_shas)
-      line_ids = line_shas.map { |sha| line_id_by_sha.fetch(sha) }
-
       ActiveRecord::Base.transaction do
         @page.lock!
 
@@ -72,6 +69,8 @@ module Wiki
           end
         end
 
+        line_id_by_sha = upsert_lines!(lines, line_shas)
+        line_ids = line_shas.map { |sha| line_id_by_sha.fetch(sha) }
         @page.update!(body: normalised)
 
         WikiVersionRecorder.record!(
@@ -94,6 +93,7 @@ module Wiki
           { wiki_revision_id: rev.id, wiki_line_id: line_id, position: pos }
         end
         WikiRevisionLine.insert_all!(rows) if rows.any?
+        record_description!(rev, normalised)
 
         rev
       end
@@ -110,6 +110,26 @@ module Wiki
 
     private
 
+    def record_description! revision, body
+      tag = @page.tag_name.tag
+      return unless tag && @page.tag_name.language_code == 'ja'
+
+      tag.lock!
+      description = TagDescription.lock.find_by(tag_id: tag.id, language_code: 'ja')
+      version_no = description ? description.version_no + 1 : 1
+      TagDescriptionVersion.create!(
+          id: revision.id, tag_id: tag.id, language_code: 'ja', version_no:,
+          event_type: description ? 'update' : 'create', body:,
+          created_by_user_id: @created_user.id, created_at: revision.created_at)
+      if description
+        description.update!(body:, version_no:, updated_by_user_id: @created_user.id)
+      else
+        TagDescription.create!(
+            id: @page.id, tag_id: tag.id, language_code: 'ja', version_no:, body:,
+            created_by_user_id: @created_user.id, updated_by_user_id: @created_user.id)
+      end
+    end
+
     def split_lines(body) = body.split("\n")
 
     def upsert_lines! lines, line_shas
diff --git a/backend/config/routes.rb b/backend/config/routes.rb
index e44f5b5..e109460 100644
--- a/backend/config/routes.rb
+++ b/backend/config/routes.rb
@@ -35,7 +35,7 @@ Rails.application.routes.draw do
 
   resources :wiki_pages, path: 'wiki', only: [:index, :show, :create, :update] do
     collection do
-      get :search, to: redirect('/')
+      get :search, action: :index
       get :changes
 
       scope :title do