tap/app/views/devise/sessions/new.html.erb

<h2>Sign in</h2>
<%= render partial: 'flash' %>

<div class="sign-in">
  <%= f_form_for(resource, :as => resource_name, :url => session_path(resource_name)) do |f| %>
    <%= f.text_field :nickname %>
    <%= f.password_field :password %>

    <% if devise_mapping.rememberable? %>
      <%= f.check_box :remember_me %>
    <% end %>

    <%= f.submit "Sign in" %>
  <% end %>
</div>

<%= render "devise/shared/links" %>