The Emotion Window, or Heart Window (ココロウィンドウ Kokoro Windou) in the Japanese games, is a mechanic introduced to the Mega Man Battle Network series, starting from Mega Man Battle Network 4. Depending on how the player performs during NetBattles, the Emotion Window can change to reflect the NetNavi's current mood, and this will affect the player's performance as long as the changes are in effect. If MegaMan.EXE is inflicted with a bug from the Navi Customizer or other sources, the Emotion Window will flicker to reflect this.
A well-known, yet risky, method, is to glitch the Humor program on purpose. This results in the Emotion Window repeatedly switching between any of MegaMan's available states, allowing a lucky player to use the attack bonus of the Full Synchro or Rage states without going through the difficulty of triggering it themselves.
- Main article: Full Synchro
Full Synchro is obtained when the player manages to perform a counter hit using a non-dimming chip attack. MegaMan glows bright blue and a pink spinning ring surrounds him. In this state, the player's next chip attack has double power, and attacking enemies will flash during the timings when they can be countered, encouraging the player to remain in Full Synchro. Full Synchro can also be obtained if the player manages to land multiple hits on the enemy/boss, the best chip to do this is the AirHoc3 in Battle Network 4
Full Synchro expires when the player is hit by an enemy attack, or when the player performs a chip attack. It cannot be accessed when MegaMan is using a Double Soul or Cross, but can be used while he is in Beast Out. Full Synchro can also be initiated while the player is controlling another Navi.
MegaMan turns Worried when he takes multiple hits without successfully retaliating. While Worried, MegaMan is unable to perform Double Soul. In Battle Network 4, Dark Chips also become available for MegaMan to use, and if MegaMan has used enough Dark Chips, he can start the battle in Worried state, with the Dark Chips already available for use. This state can be lifted by successfully retaliating, and even entering Full Synchro. The Worried state is unavailable in Battle Network 6.
- Main article: Dark Soul
Evil state is obtained when the player has used a Dark Chip. MegaMan turns dark, gains access to the DS Navi chips and other Battle Chips exclusive to Evil MegaMan, but is unable to use SP Navi chips and other chips such as Sanctuary. MegaMan also loses the ability to use Double Souls (except Dark Soul) or enter Full Synchro.
Once per battle, if MegaMan would be deleted, he remains at 1 HP and unites with his Dark Soul. Through this unique Double Soul, MegaMan turns completely black, becoming invincible but uncontrollable for several seconds. He then moves and attacks randomly with Buster shots, loaded chips, or any chips and Program Advances which the player has previously used.
If MegaMan has used enough Dark Chips, he can start the battle in Evil state. In Battle Network 4, this also means that Dark Chips become available for use immediately. Evil state and Dark Soul is unavailable in Battle Network 6 because the Dark Chips are destroyed along with the base of Dark Chip Syndicate Nebula at the end of Battle Network 5.
Because no other Navi has a Dark Emotion Window programmed into them, other Navis under the player's control cannot use Dark Chips - they will simply fail to work (like an Atk+10 chip on its own) if the player attempts to use one that way.
If MegaMan takes over 300 damage in one hit, or just broke free from a status effect without any effort in reducing its duration, he enters an Angry state. Here, he gains Super Armor, meaning his attacks cannot be interrupted, and his next chip attack has doubled strength. Unlike Full Synchro, Angry does not expire when MegaMan gets hit, but instead dissipates over time, or once he uses a chip attack.
Available only in the DS remake of Battle Network 5, the Pinch state triggers if the player performs poorly in battle, like taking a large amount of damage and falling to low HP. The player can then blow into the microphone to give the current Navi 2 of the following bonuses:
- Instant Full Synchro
- Free 100 HP Barrier
- 300 HP restored
This state can be obtained while controlling any Navi.
Replacing the Worried state in Battle Network 6, the Tired state is obtained once MegaMan's emotion counter reaches 0 due to use of Beast Out. Much like the Worried state, MegaMan cannot enter Full Synchro, though he is still capable of using Crosses (each Cross has a unique sprite if initiated while Tired). If MegaMan attempts to initiate Beast Out a second time during battle, he instead enters Beast Over, where he goes completely berserk for a turn.
If MegaMan enters a battle in this state, he cannot initiate Beast Out or Beast Over at all.
When MegaMan enters any of the above transformations, his Emotion Window changes accordingly to reflect it. While the transformation is in effect, MegaMan cannot enter any other emotional state. Beast Out is an exception, being able to use Full Synchro. Crosses also have their own sprites if they are used while MegaMan is Tired.
Double Souls and Beast Out use a timer on the right edge of the Emotion Window. Once said timer reaches zero, the transformation expires.
If MegaMan has yet to finish off the opponent after entering Beast Over in Battle Network 6, he enters the Very Tired state the moment the Custom Gauge fills and Beast Over expires. MegaMan suffers from a severe HP glitch that will rapidly plummet his health gauge to 1, his Buster stats are all reduced to 1, and he cannot initiate any transformations.