Apex domains cannot have CNAME records.
Question and response
Question
dig willap.jp. NS
Answer
willap.jp. 5 NS ns-908.awsdns-49.net.
willap.jp. 5 NS ns-242.awsdns-30.com.
willap.jp. 5 NS ns-1862.awsdns-40.co.uk.
willap.jp. 5 NS ns-1050.awsdns-03.org.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0