Apex domains cannot have CNAME records.
Question and response
Question
dig mitene.jp. NS
Answer
mitene.jp. 5 NS nsx2.mitene.ad.jp.
mitene.jp. 5 NS nsx1.mitene.ad.jp.
Authority
The response has no authority records.
Additional
nsx1.mitene.ad.jp. 5 A 218.219.161.1
nsx2.mitene.ad.jp. 5 A 218.219.162.122
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0