Apex domains cannot have CNAME records.
Question and response
Question
dig linecorp.com. NS
Answer
linecorp.com. 5 NS ns1.naver.jp.
linecorp.com. 5 NS ns2.naver.jp.
linecorp.com. 5 NS ans1.linecorp.com.
linecorp.com. 5 NS ans2.linecorp.com.
Authority
The response has no authority records.
Additional
ns1.naver.jp. 5 A 147.92.152.224
ns2.naver.jp. 5 A 147.92.162.216
ans1.linecorp.com. 5 A 147.92.247.1
ans2.linecorp.com. 5 A 43.223.24.1
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0