backend/app/models/tag.rb

@@ -73,6 +73,10 @@ class Tag < ApplicationRecord
     @bot ||= find_or_create_by_tag_name!('bot操作', category: :meta)
   end
 
+  def self.no_deerjikist
+    @no_deerjikist ||= find_or_create_by_tag_name!('ニジラー情報不詳', category: :meta)
+  end
+
   def self.video
     @video ||= find_or_create_by_tag_name!('動画', category: :meta)
   end
@@ -97,6 +101,7 @@ class Tag < ApplicationRecord
     end
 
     tags << Tag.tagme if with_tagme && tags.size < 10 && tags.none?(Tag.tagme)
+    tags << Tag.no_deerjikist if tags.all? { |t| t.category != 'deerjikist' }
     tags.uniq(&:id)
   end
 

backend/lib/tasks/sync_nico.rake

@@ -2,9 +2,9 @@ namespace :nico do
   desc 'ニコニコ DB 同期'
   task sync: :environment do
     require 'json'
-    require 'open3'
-    require 'open-uri'
     require 'nokogiri'
+    require 'open-uri'
+    require 'open3'
     require 'set'
     require 'time'
 
@@ -117,6 +117,9 @@ namespace :nico do
       if kept_non_nico_ids.to_set != desired_non_nico_ids.to_set
         desired_all_ids << Tag.bot.id
       end
+      unless Tag.where(id: desired_all_ids).where(category: 'deerjikist').exists?
+        desired_all_ids << Tag.no_deerjikist.id
+      end
       desired_all_ids.uniq!
 
       sync_post_tags!(post, desired_all_ids, current_ids: kept_ids)