Muramasa

Muramasa (ムラマサ) is a dark sword from the Mega Man Battle Network and Mega Man Star Force series that can be used as a Battle Chip or Battle Card.

Muramasa
Muramasa (ムラマサ) is a sword Battle Chip obtained from ShadowMan.EXE. It slashes one square ahead. The damage it causes increases as the user's HP lowers. ShadowMan himself is also capable of using this attack while low on health, which can be lethal as it could do upwards of 1000 damage in one hit.

Mega Man Battle Network

Mega Man Battle Network 2

Mega Man Network Transmission

Mega Man Battle Chip Challenge

Muramasa Blade
The Muramasa Blade (ムラマサブレード), shortened as Muramasa outside Japan, is a slightly different version of the Muramasa Battle Chip. It cuts two squares ahead. Its attack power is the difference of the user's current HP and maximum HP, but caps off at 500 from the fourth game onwards.

Mega Man Battle Network 3

Mega Man Battle Network 4

Mega Man Battle Network 5

Mega Man Battle Network 6

Rockman.EXE 4.5 Real Operation

Battle Card
Muramasa (Muramasa Blade in Japan) is a Standard Battle Card in Mega Man Star Force 2 and Mega Man Star Force 3. It cannot be obtained normally in either game. In Mega Man Star Force 2, it can only be obtained by entering a Wave Command Code for a Blank Card, while in Mega Man Star Force 3 it appears only as Illegal Data.

Much like its Battle Chip predecessor, Muramasa deals damage equal to the amount of HP the user has lost. Its damage is capped at 500 and it hits 2 panels deep.

Other media
Muramasa appeared in the MegaMan NT Warrior manga, where Serenade.EXE gave it to ProtoMan.EXE.