Apex domains cannot have CNAME records.
Question and response
Question
dig m-defender.jp. NS
Answer
m-defender.jp. 5 NS ns103.nameserver.ne.jp.
m-defender.jp. 5 NS ns3.nameserver.ne.jp.
m-defender.jp. 5 NS ns4.nameserver.ne.jp.
Authority
The response has no authority records.
Additional
ns3.nameserver.ne.jp. 4 A 121.83.254.253
ns4.nameserver.ne.jp. 4 A 121.83.254.252
ns103.nameserver.ne.jp. 5 A 210.239.33.4
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0