Apex domains cannot have CNAME records.
Question and response
Question
dig activejapan.site. NS
Answer
activejapan.site. 5 NS ns-638.awsdns-15.net.
activejapan.site. 5 NS ns-1266.awsdns-30.org.
activejapan.site. 5 NS ns-1965.awsdns-53.co.uk.
activejapan.site. 5 NS ns-507.awsdns-63.com.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0