Muramasa

Muramasa (ムラマサ) is a dark sword from the Mega Man Battle Network and Mega Man Star Force series based on Muramasa that mainly appears as a Battle Chip or Battle Card.

Muramasa
Muramasa (ムラマサ) is a sword used by ShadowMan that can be obtained from him as a Battle Chip. 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

Although it cannot be obtained in Mega Man Battle Network 5, Muramasa appears alongside ShadowMan in the Team Colonel version.

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 999 and 500 from the fourth and sixth game onwards respectively.

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.

Rockman.EXE Stream
Muramasa Blade is used by ShadowMan.

MegaMan NT Warrior (manga)
Muramasa (Muramasa Blade in Japan) appeared in the MegaMan NT Warrior manga as a blade forged to combat the Dark Power. Serenade gave it to ProtoMan so he could destroy the Dark Power. This super-natural sword carries the burden of the wearer having to fight against the Dark Power until the end, not stopping even if he is heavily injured or feeling pain. However, the more damage the user sustains, the higher its power will be. ProtoMan also gains the Muramasa Style Change with it.

ProtoMan used Muramasa to defeat the Forces of Darkness and LaserMan. In the final chapter, he asks a swordsmith to reforge Muramasa, giving its blade the ability to split into three.