diff --git a/app/models/concerns/searchable.rb b/app/models/concerns/searchable.rb
index 9b701f3adfd..866c861e190 100644
--- a/app/models/concerns/searchable.rb
+++ b/app/models/concerns/searchable.rb
@@ -15,7 +15,7 @@ def search_by_keywords(searched_values = {})
     end
 
     def columns_for_keyword_search(*column_names)
-      define_singleton_method(:_join_column_names) { "#{column_names.join('_or_')}_cont_any" }
+      define_singleton_method(:_join_column_names) { "#{(column_names + %i[kana_name]).join('_or_')}_cont_any" }
     end
 
     private
@@ -23,23 +23,16 @@ def columns_for_keyword_search(*column_names)
     def params_for_keyword_search(searched_values = {})
       return {} if searched_values[:word].blank?
 
-      groupings = searched_values[:word].split(/[[:blank:]]+/).map do |word|
-        if word.start_with?('user:')
-          create_parameter_for_search_user_id(word.delete_prefix('user:'))
-        else
-          { _join_column_names => word }
-        end
-      end
+      word = searched_values[:word].strip
 
-      { combinator: 'or', groupings: }
+      { combinator: 'or', groupings: [word_to_groupings(word)] }
     end
 
     def word_to_groupings(word)
       return { _join_column_names => word } if COLUMN_NAMES_FOR_SEARCH_USER_ID.none? { |column_name| has_attribute?(column_name) }
 
-      case word
-      when /user:(.*)/
-        create_parameter_for_search_user_id(Regexp.last_match(1))
+      if word.match?(/^user:/)
+        create_parameter_for_search_user_id(word.delete_prefix("user:"))
       else
         { _join_column_names => word }
       end
@@ -51,7 +44,7 @@ def split_keyword_by_blank(word)
 
     def create_parameter_for_search_user_id(username)
       user = User.find_by(login_name: username)
-      { "#{COLUMN_NAMES_FOR_SEARCH_USER_ID.join('_or_')}_eq" => user&.id || 0 }
+      { "#{%i[user_id last_updated_user_id].join('_or_')}_eq" => user&.id || 0 }
     end
   end
 
diff --git a/app/models/search_user.rb b/app/models/search_user.rb
index 95da53c75bf..5de2d4c3a76 100644
--- a/app/models/search_user.rb
+++ b/app/models/search_user.rb
@@ -10,7 +10,9 @@ def initialize(word:, users: nil, target: nil, require_retire_user: false)
 
   def search
     validated_search_word = validate_search_word
-    searched_user = @users ? @users.merge(User.search_by_keywords(word: validated_search_word)) : User.search_by_keywords(word: validated_search_word)
+    return User.none if validated_search_word.blank?
+
+    searched_user = @users ? @users.merge(User.search_by_keywords(word: validated_search_word, exact_match: true)) : User.search_by_keywords(word: validated_search_word, exact_match: true)
 
     if @target == 'retired'
       searched_user.unscope(where: :retired_on).retired
@@ -23,6 +25,8 @@ def search
 
   def validate_search_word
     stripped_word = @word.strip
+    return nil if stripped_word.blank?
+
     if stripped_word.match?(/^[\w-]+$/)
       stripped_word if stripped_word.length >= 3
     elsif stripped_word.length >= 2