diff --git a/ga/conf/locale/ja_JP/LC_MESSAGES/gacco.po b/ga/conf/locale/ja_JP/LC_MESSAGES/gacco.po
index 2c83fc69d995..c1b28c5e4b3b 100644
--- a/ga/conf/locale/ja_JP/LC_MESSAGES/gacco.po
+++ b/ga/conf/locale/ja_JP/LC_MESSAGES/gacco.po
@@ -2281,6 +2281,14 @@ msgstr "半角英数{password_min_length}文字以上"
 msgid "It includes single-byte uppercase and lowercase letters, numbers, one or more characters"
 msgstr "半角アルファベットの大文字、小文字、数字を1文字以上含めてください"
 
+#: openedx/core/djangoapps/user_api/views.py
+msgid "Alphanumeric characters {min_length} or more characters, {max_length} characters or less"
+msgstr "半角英数{min_length}文字以上、{max_length}文字以下"
+
+#: openedx/core/djangoapps/user_api/views.py
+msgid "I agree to the {platform_name} {terms_of_service}."
+msgstr "{terms_of_service}に同意"
+
 #-#-#-#-#  Original messages in gacco/templates  #-#-#-#-#
 
 #: templates/theme-header.html
diff --git a/openedx/core/djangoapps/user_api/tests/test_views.py b/openedx/core/djangoapps/user_api/tests/test_views.py
index 92fa8c3d0b71..8472b8154376 100644
--- a/openedx/core/djangoapps/user_api/tests/test_views.py
+++ b/openedx/core/djangoapps/user_api/tests/test_views.py
@@ -880,7 +880,7 @@ def test_register_form_default_fields(self):
                 u"required": True,
                 u"label": u"Public username",
                 u"placeholder": u"JaneDoe",
-                u"instructions": u"The name that will identify you in your courses - <strong>(cannot be changed later)</strong>",
+                u"instructions": u"Alphanumeric characters 2 or more characters, 30 characters or less<br>The name that will identify you in your courses - <strong>(cannot be changed later)</strong>",
                 u"restrictions": {
                     "min_length": USERNAME_MIN_LENGTH,
                     "max_length": USERNAME_MAX_LENGTH
@@ -969,7 +969,7 @@ def test_register_form_third_party_auth_running(self):
                     u"required": True,
                     u"label": u"Public username",
                     u"placeholder": u"JaneDoe",
-                    u"instructions": u"The name that will identify you in your courses - <strong>(cannot be changed later)</strong>",
+                    u"instructions": u"Alphanumeric characters 2 or more characters, 30 characters or less<br>The name that will identify you in your courses - <strong>(cannot be changed later)</strong>",
                     u"restrictions": {
                         "min_length": USERNAME_MIN_LENGTH,
                         "max_length": USERNAME_MAX_LENGTH
diff --git a/openedx/core/djangoapps/user_api/views.py b/openedx/core/djangoapps/user_api/views.py
index 38c6fc25a639..27e6bce79c43 100644
--- a/openedx/core/djangoapps/user_api/views.py
+++ b/openedx/core/djangoapps/user_api/views.py
@@ -390,6 +390,8 @@ def _add_username_field(self, form_desc, required=True):
         # Translators: These instructions appear on the registration form, immediately
         # below a field meant to hold the user's public username.
         username_instructions = _(
+            u"Alphanumeric characters {min_length} or more characters, {max_length} characters or less"
+        ).format(min_length=2, max_length=30) + "<br>" + _(
             u"The name that will identify you in your courses - "
             "{bold_start}(cannot be changed later){bold_end}"
         ).format(bold_start=u'<strong>', bold_end=u'</strong>')