It can be anything! An apex, subdomain, or even a URL.

Results forcode.update.jp

Logged At	Not Before	Not After	Common Name	Matching Identities	Issuer Name
2019-10-15T00:14:28.005	2019-10-14T23:14:27	2020-01-12T23:14:27	porn.ryukyu	code.update.jp	C=US, O=Let's Encrypt, CN=Let's Encrypt Authority X3
2019-10-15T00:14:27.452	2019-10-14T23:14:27	2020-01-12T23:14:27	porn.ryukyu	code.update.jp	C=US, O=Let's Encrypt, CN=Let's Encrypt Authority X3
2019-08-14T14:46:40.586	2019-08-14T13:46:39	2019-11-12T13:46:39	fibertel.acordar.app	code.update.jp	C=US, O=Let's Encrypt, CN=Let's Encrypt Authority X3
2019-08-14T14:46:39.723	2019-08-14T13:46:39	2019-11-12T13:46:39	fibertel.acordar.app	code.update.jp	C=US, O=Let's Encrypt, CN=Let's Encrypt Authority X3
2019-06-14T16:49:16.432	2019-06-14T15:49:14	2019-09-12T15:49:14	concursotradeup.com	code.update.jp	C=US, O=Let's Encrypt, CN=Let's Encrypt Authority X3
2019-06-14T16:49:15.008	2019-06-14T15:49:14	2019-09-12T15:49:14	concursotradeup.com	code.update.jp	C=US, O=Let's Encrypt, CN=Let's Encrypt Authority X3
2019-06-14T15:03:17.687	2019-06-14T14:03:16	2019-09-12T14:03:16	code.update.jp	code.update.jp	C=US, O=Let's Encrypt, CN=Let's Encrypt Authority X3
2019-06-14T15:03:16.869	2019-06-14T14:03:16	2019-09-12T14:03:16	code.update.jp	code.update.jp	C=US, O=Let's Encrypt, CN=Let's Encrypt Authority X3