Apex domains cannot have CNAME records.
Question and response
Question
dig kamome.or.jp. NS
Answer
kamome.or.jp. 1 NS dns3.kamome.or.jp.
kamome.or.jp. 1 NS dns1.kamome.or.jp.
kamome.or.jp. 1 NS dns2.kamome.or.jp.
Authority
The response has no authority records.
Additional
dns1.kamome.or.jp. 1 A 218.45.16.69
dns2.kamome.or.jp. 1 A 218.45.29.109
dns3.kamome.or.jp. 1 A 15.168.4.91
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0