diff --git a/l10n_jp_summary_invoice/i18n/ja.po b/l10n_jp_summary_invoice/i18n/ja.po
index 5c82392..ae371df 100644
--- a/l10n_jp_summary_invoice/i18n/ja.po
+++ b/l10n_jp_summary_invoice/i18n/ja.po
@@ -257,6 +257,11 @@ msgstr "参照"
 msgid "Remit-to Bank"
 msgstr "振込先銀行"
 
+#. module: l10n_jp_summary_invoice
+#: model:ir.model.fields,field_description:l10n_jp_summary_invoice.field_account_billing__report_subtitle
+msgid "Report Subtitle"
+msgstr "帳票サブタイトル"
+
 #. module: l10n_jp_summary_invoice
 #: model:ir.model.fields,field_description:l10n_jp_summary_invoice.field_account_tax__rounding_adjustment
 msgid "Rounding Adjustment"
@@ -296,6 +301,11 @@ msgid ""
 "Specify the header remark to be displayed on the printed summary invoice"
 msgstr "合計請求書ヘッダーに表示するコメントを指定してください"
 
+#. module: l10n_jp_summary_invoice
+#: model:ir.model.fields,help:l10n_jp_summary_invoice.field_account_billing__report_subtitle
+msgid "Subtitle to be printed below the title of the summary invoice report."
+msgstr "合計請求書のタイトルの下に表示されるサブタイトル。"
+
 #. module: l10n_jp_summary_invoice
 #: model_terms:ir.ui.view,arch_db:l10n_jp_summary_invoice.report_summary_invoice_document
 msgid "Summary Invoice"
diff --git a/l10n_jp_summary_invoice/i18n/l10n_jp_summary_invoice.pot b/l10n_jp_summary_invoice/i18n/l10n_jp_summary_invoice.pot
index 7ac5650..9e7a389 100644
--- a/l10n_jp_summary_invoice/i18n/l10n_jp_summary_invoice.pot
+++ b/l10n_jp_summary_invoice/i18n/l10n_jp_summary_invoice.pot
@@ -256,6 +256,11 @@ msgstr ""
 msgid "Remit-to Bank"
 msgstr ""
 
+#. module: l10n_jp_summary_invoice
+#: model:ir.model.fields,field_description:l10n_jp_summary_invoice.field_account_billing__report_subtitle
+msgid "Report Subtitle"
+msgstr ""
+
 #. module: l10n_jp_summary_invoice
 #: model:ir.model.fields,field_description:l10n_jp_summary_invoice.field_account_tax__rounding_adjustment
 msgid "Rounding Adjustment"
@@ -295,6 +300,11 @@ msgid ""
 "Specify the header remark to be displayed on the printed summary invoice"
 msgstr ""
 
+#. module: l10n_jp_summary_invoice
+#: model:ir.model.fields,help:l10n_jp_summary_invoice.field_account_billing__report_subtitle
+msgid "Subtitle to be printed below the title of the summary invoice report."
+msgstr ""
+
 #. module: l10n_jp_summary_invoice
 #: model_terms:ir.ui.view,arch_db:l10n_jp_summary_invoice.report_summary_invoice_document
 msgid "Summary Invoice"
diff --git a/l10n_jp_summary_invoice/models/account_billing.py b/l10n_jp_summary_invoice/models/account_billing.py
index 295e4d6..cd3dde7 100644
--- a/l10n_jp_summary_invoice/models/account_billing.py
+++ b/l10n_jp_summary_invoice/models/account_billing.py
@@ -49,6 +49,9 @@ class AccountBilling(models.Model):
         help="If not specified, the first bank account linked to the company will show "
         "in the report.",
     )
+    report_subtitle = fields.Char(
+        help="Subtitle to be printed below the title of the summary invoice report.",
+    )
 
     @api.constrains("state", "billing_line_ids")
     def _check_account_move_billability(self):
diff --git a/l10n_jp_summary_invoice/reports/report_summary_invoice_templates.xml b/l10n_jp_summary_invoice/reports/report_summary_invoice_templates.xml
index c6a489d..9485d1b 100644
--- a/l10n_jp_summary_invoice/reports/report_summary_invoice_templates.xml
+++ b/l10n_jp_summary_invoice/reports/report_summary_invoice_templates.xml
@@ -151,6 +151,9 @@
                         >Cancelled Summary Invoice</span>
                         <span t-field="o.name" />
                     </h2>
+                    <h4 t-if="o.report_subtitle" class="mt-1 fw-normal">
+                        <span t-field="o.report_subtitle" />
+                    </h4>
                     <div t-if="o.company_id.summary_invoice_remark">
                         <span t-field="o.company_id.summary_invoice_remark" />
                     </div>
diff --git a/l10n_jp_summary_invoice/static/description/index.html b/l10n_jp_summary_invoice/static/description/index.html
index b636a6d..06dc97d 100644
--- a/l10n_jp_summary_invoice/static/description/index.html
+++ b/l10n_jp_summary_invoice/static/description/index.html
@@ -8,11 +8,10 @@
 
 /*
 :Author: David Goodger (goodger@python.org)
-:Id: $Id: html4css1.css 9511 2024-01-13 09:50:07Z milde $
+:Id: $Id: html4css1.css 8954 2022-01-20 10:10:25Z milde $
 :Copyright: This stylesheet has been placed in the public domain.
 
 Default cascading style sheet for the HTML output of Docutils.
-Despite the name, some widely supported CSS2 features are used.
 
 See https://docutils.sourceforge.io/docs/howto/html-stylesheets.html for how to
 customize this style sheet.
@@ -275,7 +274,7 @@
   margin-left: 2em ;
   margin-right: 2em }
 
-pre.code .ln { color: gray; } /* line numbers */
+pre.code .ln { color: grey; } /* line numbers */
 pre.code, code { background-color: #eeeeee }
 pre.code .comment, code .comment { color: #5C6576 }
 pre.code .keyword, code .keyword { color: #3B0D06; font-weight: bold }
@@ -301,7 +300,7 @@
 span.pre {
   white-space: pre }
 
-span.problematic, pre.problematic {
+span.problematic {
   color: red }
 
 span.section-subtitle {
@@ -468,9 +467,7 @@ <h2><a class="toc-backref" href="#toc-entry-6">Contributors</a></h2>
 <div class="section" id="maintainers">
 <h2><a class="toc-backref" href="#toc-entry-7">Maintainers</a></h2>
 <p>This module is maintained by the OCA.</p>
-<a class="reference external image-reference" href="https://odoo-community.org">
-<img alt="Odoo Community Association" src="https://odoo-community.org/logo.png" />
-</a>
+<a class="reference external image-reference" href="https://odoo-community.org"><img alt="Odoo Community Association" src="https://odoo-community.org/logo.png" /></a>
 <p>OCA, or the Odoo Community Association, is a nonprofit organization whose
 mission is to support the collaborative development of Odoo features and
 promote its widespread use.</p>
diff --git a/l10n_jp_summary_invoice/views/account_billing_views.xml b/l10n_jp_summary_invoice/views/account_billing_views.xml
index dcda96d..8a39ad6 100644
--- a/l10n_jp_summary_invoice/views/account_billing_views.xml
+++ b/l10n_jp_summary_invoice/views/account_billing_views.xml
@@ -52,6 +52,7 @@
             <xpath expr="//field[@name='payment_paid_all']" position="after">
                 <field name="company_partner_id" invisible="1" />
                 <field name="remit_to_bank_id" invisible="bill_type != 'out_invoice'" />
+                <field name="report_subtitle" />
             </xpath>
             <xpath expr="//field[@name='date']" position="after">
                 <field name="date_due" invisible="bill_type != 'out_invoice'" />