Apex domains cannot have CNAME records.
Question and response
Question
dig mediagalaxy.ne.jp. NS
Answer
mediagalaxy.ne.jp. 5 NS ns008-vcb09s9popki02pd.v.d-53.net.
mediagalaxy.ne.jp. 5 NS ns008-vcb09s9popki02pd.v.d-53.jp.
mediagalaxy.ne.jp. 5 NS ns008-vcb09s9popki02pd.v.d-53.info.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0