Apex domains cannot have CNAME records.
Question and response
Question
dig broadline.ne.jp. NS
Answer
broadline.ne.jp. 5 NS ns015-38eld86fjcnreds0.3.d-53.net.
broadline.ne.jp. 5 NS ns015-38eld86fjcnreds0.3.d-53.jp.
broadline.ne.jp. 5 NS ns015-38eld86fjcnreds0.3.d-53.info.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0