I didn't find the chance to catch that person's gameplay these few days, but I do find out that account might be linked to two of the "17" account which also got reported hacking before.

That is the reported account:
https://battlelog.battlefield.com/bf4/ja/soldier/17IME/stats/1004732122127/pc/

The two of it look similar:

https://battlelog.battlefield.com/bf4/ja/soldier/17Monet/stats/1004664213527/pc/

https://battlelog.battlefield.com/bf4/ja/soldier/17Midari/stats/1004210749085/pc/

Battle report:

https://battlelog.battlefield.com/bf4/ja/battlereport/show/1/1296869814893224704/1004732122127/