Apex domains cannot have CNAME records.
Question and response
Question
dig hus.aics.ne.jp. NS
Answer
hus.aics.ne.jp. 5 NS ns11.aics.ad.jp.
hus.aics.ne.jp. 5 NS ns13.aics.ad.jp.
hus.aics.ne.jp. 5 NS ns12.aics.ad.jp.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0