Apex domains cannot have CNAME records.
Question and response
Question
dig mwjp.jp. NS
Answer
mwjp.jp. 5 NS ns.elmc.co.jp.
mwjp.jp. 5 NS ns2.elmc.co.jp.
Authority
The response has no authority records.
Additional
ns.elmc.co.jp. 5 A 103.239.18.56
ns2.elmc.co.jp. 5 A 210.152.246.30
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0