Apex domains cannot have CNAME records.
Question and response
Question
dig fsi.ne.jp. NS
Answer
fsi.ne.jp. 4 NS ns-1577.awsdns-05.co.uk.
fsi.ne.jp. 4 NS ns-407.awsdns-50.com.
fsi.ne.jp. 4 NS ns-863.awsdns-43.net.
fsi.ne.jp. 4 NS ns-1370.awsdns-43.org.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0