CirKill (サーキラー Sākirā?, "Cirkiller" in Japan) is a virus in the Mega Man Battle Network series that only appears in Mega Man Battle Network 4. CirKills move around the enemy's side in a circle, firing at MegaMan whenever he steps onto their row. The best way to deal with these is to use the ElemIce chip on an ice panel, and doing this usually gives a counterattack when done correctly.