This article is about the Duo NetNavi. For his anime counterpart, see Duo.EXE (anime). For his robot counterpart, see Duo.

Duo (デューオ Dyūo) is a mysterious alien computer program from outer space in the Mega Man Battle Network series.


Duo is a perfectly neutral figure who goes purely on logic as he judges other beings from their planets, whether the species or race is good or evil, the latter of which would lead him to destroy the planet, as his primary mission is to destroy all evil in the universe.

He wished to destroy Earth because its inhabitants were too deep in their darkness and were evil, and even after seeing MegaMan defeat his darkness after Duo drew it out from him, Duo stated that MegaMan hadn't destroyed the darkness, just suppressed it, making him deem humanity still too evil to leave alone.

However, he is not without mercy or reason. When any being, such as Lan and MegaMan, has shown him the possibility of hope for humanity, Duo is likely to spare the planet and give it a test to prove itself, and would return in future times to test humanity again.


Duo was introduced in Mega Man Battle Network 4, at the very end of the game as the final boss. Duo is the operation system for an asteroid-based rocket poised to destroy Earth. The villainous Dr. Regal attempts to control Duo, and the program itself acts as judge of the human race, deeming it evil and unworthy of survival. For this reason, Duo intends to destroy the planet, effectively eradicating the species so that there is not a single trace of evil energy left.

When MegaMan entered the control system of the asteroid, Duo sensed the Dark Soul inside MegaMan and confronted him as a large head. Duo explained to MegaMan that he exists to destroy all evil beings and explained that while humans were intelligent, they were evil and must be eradicated. Duo even stated that MegaMan was evil before he forced MegaMan DS out of MegaMan's body and had the two face off. Despite MegaMan's victory, Duo explained that MegaMan only managed to suppress his darkness, rather than destroy it, and therefore meant that he is not strong enough to destroy evil. MegaMan refuted saying that everyone has darkness inside them, but they would try to fight it to make sure that it never takes over.

Restating his purpose for creation was to destroy all evil, Duo takes on his battle form, summoning his body, arms, and helmet before he faced off against MegaMan. Despite the odds, MegaMan ultimately emerged victorious, destroying Duo's battle form. Duo was shocked that his battle mode was defeated, but claimed that it was too late to change the asteroid's course and won't be long before it entered Earth's atmosphere. Seeing that MegaMan was still determined to go on, Duo granted passage to MegaMan to the control system. 

However, as Duo surmised, MegaMan was too weak to change the asteroid's course and continued to countdown until they reached Earth's atmosphere and said that MegaMan should just give up. However, much to his surprise, the asteroid's systems could feel much vibrations coming from the Earth's atmosphere. He turned the vibration sensors on and then could hear everyone in the planet shouting out MegaMan's name. Duo did not think that it mattered much before he saw MegaMan suddenly display a great increase in strength, moving the system a bit. Using all their energy, Lan and MegaMan performed a Full Synchro and finally altered the asteroid's course, thus avoiding Earth's destruction from a collision with the asteroid, before the two passed out. 

Duo was impressed by their showing of unity and the power that came from it, before stating that he would one day return, whether it would be decades or even centuries from now. He then gave his farewells to MegaMan and sent him back to Lan. 

Although his story essentially ends at the game's conclusion, he makes anonymous appearances in Mega Man Battle Network 5 and 6, saying that he is watching both Lan and MegaMan and aiding their quest against evil by providing powerful chips that takes after one of his signature attacks. These occur in the Nebula Area and the Graveyard.

Yamato Man


Main article: Duo.EXE (anime)

Duo is a godlike entity in the anime. He had destroyed the Earth, but turned back time so individuals that has the potential of Cross Fusion can prove and merit it's survival.

Yamato Spear


Duo, compared to and like most final bosses in the BN series from BN4 onwards, has a total of four different versions. However, each version must be fought on different save files, depending on the difficulty selected, and the final version, like with most of the Omega versions, must be unlocked by unlocking all of the 7 special icons on the start menu.

Also, unlike most final bosses and like most of the Navi bosses in Battle Network 4, Duo has a different coloration for his final version. He is fought in the Control Area in the Meteor Comp 5. The player first must fight a sub boss in the form of MegaMan DS, then proceed on to the final battle with Duo himself. During this time with the cutscenes and battles upon entering the Meteor Comp 5, it's not possible to save.

  • Duo (デューオ Dyūo), 2000 HP:
    It's the default version of the final boss of both versions of BN4, and only on Normal Mode. This version of Duo causes his ring riff to shift up to 5 times during his Destroy Laser attack. Duo here is colored with a shade of white, blue green and red, and stays colored like so for his two next subsequent versions.
  • Duo Alpha (Duoα), known as Duo V2 (デューオV2) in Japan, 2500 HP:
    It's the same as the initial version, only he is fought on Hard Mode. His Destroy Laser ring shifts positions up to 6 times instead.
  • Duo Beta (Duoβ), known as Duo V3 (デューオV3) in Japan, 3000 HP:
    It's instead fought on Super Hard Mode. His Destroy Laser ring has a total 7 position shifts. This version can be fought repeatedly until Duo Ω is unlocked.
  • Duo Omega (DuoΩ), known as Duo SP (デューオSP) in Japan, 3500 HP:
    It's the final version of Duo, this time with a gold, gray, orange and magenta coloration and his moves are boosted by 100-150 damage from his original default version. Once this version is available, it will replace the original version no matter the difficulty, as it is fought in the place of the all other versions upon obtaining the 7 special icons while being able to fight it repeatedly.


Duo possesses a variety of extremely potent abilities, many of them manifesting themselves in the form of space-age weaponry. Duo's only weak spot is at his chest cavity when it glows red. As he floats in space with no panels, ground-based attacks can't harm him. Duo's cannon is meant to be his weak-point, and despite his panel area's comp. Unlike many final bosses, it's possible to Area Grab his visible side of the field.

  • Duo Missile (デューオミサイル Dyūo Misairu):
    Duo shoots missiles from its chest, occasionally paired with Duo Yura. The missiles home in on MegaMan's row, and the mines travel in a 2x2 wave pattern. The missiles can be shot down, but has more HP the higher version it is.
  • Duo Yura (デューオユラ Dyūo Yura):
    Duo shoots mines from its chest, occasionally paired with Duo Missile. The mines travel in a 2x2 wave pattern. The Yura can be shot down, but has more HP the higher version it is.
  • Justice Fist (ジャスティスフィスト Jasutisu Fisuto):
    Duo smashes a 2x2 fist on MegaMan's field.
  • Meteor Knuckle (メテオナックル Meteo Nakkuru):
    Panels flash, and Duo rains his fists down on MegaMan's field, cracking them.
  • Big Hook (ギガントフック Giganto Fukku, Gigant Hook):
    Sweeps two lightning-fast fist two columns behind and in front.
  • Destroy Laser (デストロイレーザー Desutoroi Rēzā):
    Fires a straight red laser shot on the center row which can fan out via a central ring riff coating the laser at certain points along the spectrum. Pierces Invis if it connects. Each version of Duo adds one extra time the ring riff appears, and it moves along a certain pattern. Duo's first version has the ring move up to 5 times, while up to the final version causes the ring to shift 8 times total.
  • Anger Impact (アンガーインパクト Angā Inpakuto):
    Duo releases a wave of energy in an echo effect that resembles a face, cracking MegaMan's two front columns. It's used if Duo is low on HP.

Battle Chips

  • Duo (デューオ Dyūo) is an event only chip from Mega Man Battle Network 4. Can only be used if the player back 2x3 rows are available. All obstacles on the field are destroyed and Duo slide in, then he performs his Meteor Knuckle attack.
  • Justice One (JustcOne) (ジャスティスワン Jasutisu Wan) is a Mega Chip from Mega Man Battle Network 5 given by Duo in the Nebula Area.
  • Meteor Knuckle (MetrKnuk) (メテオナックル Meteo Nakkuru) is a Giga Chip that launches punches like meteors. This is a modified version of his BN4 chip, however Duo himself no longer appears.
  • Big Hook (BigHook), known as Gigant Hook (ギガントフック Giganto Fukku) in Japan, is a Giga Chip where two giant sweep the enemy field, with the center column getting hit twice.

Meteor Knuckle and Big Hook are given anonymously by Duo, each in one of the game versions their appear. In Mega Man Battle Network 5 he gives the chip after MegaMan defeats Chaos Lord. In Mega Man Battle Network 6 he sends the chip via e-mail when MegaMan enters the Graveyard area.

Battle Chip ID Battle Chip Description Attack Element Code Memory Rarity
Secret Chip BN4GChip006.png Duo
MetrKnukl of justic rain down 200 BC Element Null.png None D 99 MB -

Battle Chip ID Battle Chip Description Attack Element Code Memory Rarity
Mega Chip 17 BN5MChip017.png JustcOne
Fist atk on center panel 280 BC Attribute Break.png Break J 90 MB *****
Giga Chip 2
(Team ProtoMan)
BN5TPGChip002.png BigHook
Gigant Hook)
Hook atk 2 sq wide 240 BC Attribute Break.png Break G 92 MB *****
Giga Chip 2
(Team Colonel)
BN5TCGChip002.png MetrKnuk
Meteors bombard from sky 100 BC Attribute Break.png Break M 90 MB *****

Battle Chip ID Battle Chip Description Attack Element Code Memory Rarity
Standard Chip 130 BN6Chip130.png JustcOne
Fist Atk on center panel 220 BC Attribute Break.png Break J 90 MB *****
Giga Chip 2
(Cybeast Gregar)
BN6GGChip002.png BigHook
Gigant Hook)
Hook atk 2 sq wide 240 BC Attribute Break.png Break H 92 MB *****
Giga Chip 2
(Cybeast Falzar)
BN6FGChip002.png MetrKnuk
Meteors bombard from sky 100 BC Attribute Break.png Break N 90 MB *****

Program Advances

Rockman.EXE Battle Chip Stadium

Class Name Element Battle Chips Details
Giga Gigant Hook
Giganto Fukku)
BC Element Null.png Null BN6GGChip002.png Gigant Hook
BN6Chip130.png Justice One
BN6Chip018.png Yo-Yo
Giga Gigant Inferno
Giganto Inferuno)
BC Element Heat.png Fire BN6GGChip002.png Gigant Hook
BN6Chip130.png Justice One
BN6Chip019.png Hell's Burner 1
Giga Gigant Voltage
Giganto Borutēji)
BC Element Elec.png Elec BN6GGChip002.png Gigant Hook
BN6Chip130.png Justice One
BN6Chip029.png Thunder Ball
Tera Tera Strike Hook
Tera Sutoraiku Fukku)
BC Element Null.png Null BN6GGChip002.png Gigant Hook
BN6Chip180.png Barrier
BN6Chip180.png Barrier



  • A Duo Soul was planned to be added to Mega Man Battle Network 4, but there wasn't enough space on the cartridge [2]. Within the game files, the framework for the soul still exist [3].
  • Duo's personality is very different from his classic counterpart, who also wanted to eradicate evil energy, but was notably less extreme in this venture.
  • Duo is the only final boss in the Battle Network series whose Omega Version has a new color scheme (gold instead of white).
  • It is interesting to note that at the end of Mega Man Battle Network 4, Duo says that he will return "decades, perhaps centuries later", which has led to speculation that Duo may appear in the Mega Man Star Force series. When Mega Man Star Force 3 was announced, many fans believed Duo to be Meteor G. This was not the case.
  • The insignia on Duo's arms is similar to that of Mega Man Star Force's icon.