He is using Aimbot.

ex )

41HS/63kill with AEK-971

http://battlelog.battlefield.com/bf4/ja/battlereport/show/1/931888766782924736/1898886018

22HS/35kil with U-100 Mk5

http://battlelog.battlefield.com/bf4/ja/battlereport/show/1/931886701762208320/1898886018

23HS/56kill ACC32% with AEK-971

http://battlelog.battlefield.com/bf4/ja/battlereport/show/1/931897050311026624/1898886018

39HS/86kill with AEK-971

http://battlelog.battlefield.com/bf4/ja/battlereport/show/1/932641664975249088/1898886018