NinJoy

NinJoy, also known as Snapper''', is a ninja virus from the Mega Man Battle Network series. The virus hides behind objects when not attacking. It uses a Kunai to attack its target. Some variants can also disappear in a poof shortly before an attacks lands on them, teleporting to another panel.

NinJoy
 NinJoy / Snapper1, known as Genin (ゲニン) in Japan, is the first version of this ninja virus. It is green with a yellow eye. In Mega Man Network Transmission, it tosses 2 kunais at once.

Ninky
 Ninky / Snapper2, known as Chunin (チューニン) in Japan, is the second version of this ninja virus. It is red with a yellow eye. In Mega Man Network Transmission, it tosses 3 kunais at once.

NinJoe
 NinJoe / Snapper3, known as Jonin (ジョーニン) in Japan, is the third version of this ninja virus. It is blue with a red eye. In Mega Man Network Transmission, it tosses 4 kunais at once.

NinJoyEX
 NinJoyEX is purple with a green eye.

NinkyEX
 NinkyEX is light blue with a dark blue eye.

NinJoeEX
 NinJoeEX is dark green with a purple eye.

Source
Sprite images found at Sprites INC