Apex domains cannot have CNAME records.
Question and response
Question
dig basmail.jp. NS
Answer
basmail.jp. 1 NS dns2.tokai.or.jp.
basmail.jp. 1 NS dns1.tokai.or.jp.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0