Apex domains cannot have CNAME records.
Question and response
Question
dig bmv.jp. NS
Answer
bmv.jp. 5 NS ns-1228.awsdns-25.org.
bmv.jp. 5 NS ns-838.awsdns-40.net.
bmv.jp. 5 NS ns-385.awsdns-48.com.
bmv.jp. 5 NS ns-1866.awsdns-41.co.uk.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0