Apex domains cannot have CNAME records.
Question and response
Question
dig secureweb.jp. NS
Answer
secureweb.jp. 5 NS ns-e.secureweb.jp.
secureweb.jp. 5 NS ns-w.secureweb.jp.
Authority
The response has no authority records.
Additional
ns-e.secureweb.jp. 5 A 202.32.219.55
ns-w.secureweb.jp. 5 A 210.138.20.115
ns-e.secureweb.jp. 5 AAAA 2001:240:bb81:0:0:0:28:55
ns-w.secureweb.jp. 5 AAAA 2001:240:bb81:0:0:0:29:115
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0