Kilby (キルブー,Kirubī) is a virus from Mega Man Battle Network 4. It attacks by warping to the top of the same column as the player and striking with its bamboo. However, if the target is on the top row, the virus won't attack.
Kilby is a brown variant with green bamboo and forest green leaves.
KilbyEX is an orange variant with light green bamboo and green leaves.
Kilbur is a blue variant with pink bamboo and forest green leaves.
KilburEX is a red variant with white bamboo and green leaves.
Kilbo is a brown variant with light blue bamboo and yellow green leaves.
KilboEX is a black variant with black bamboo and gray leaves.
Side Bamboo (サイドバンブー,Side Bamboo) is the Battle Chip from the Kilby family. A Kilby appears attacks from the side.
Although not dropped by Kilby, Lance, known as Bamboo Lance (バンブーランス,Bamboo Lance) in Japan, is a Battle Chip that attacks the three panels in the back of the opponent's area and pushes the targets forward. This chip appeared before and more than the virus.
Lance has a Dark Chip named Dark Lance (ダークランス,Dark Lance). In the fourth game it does normal damage equal to half of the HP of the opponent with the most hit points, and the user suffers a glitch where 5 random chips that have not been used are removed from the Folder for the battle. In the fifth game it deals Wood damage and the user suffers from a glitch where he becomes confused every time he gets hit.