実装
class Users::RegistrationsController < Devise::RegistrationsController
def confirm
end
protected
# The path used after sign up for inactive accounts.
def after_inactive_sign_up_path_for(resource)
confirm_users_sign_up_path
# あとはroutingとviewを作る
end
end
大体のことは...
overrideできるのでgithubを読むと良い
devise/app/controllers/devise/registrations_controller.rb