Cold Heart

Cold Heart(感情的な死[コールド・ハート]; Kōrudo hāto), also known as Death of Emotions, considered one of the most whicked and Evil Sacred Gears ever created, is the Sacred Gear of Shinobu Akira. It has the ability to devoid it's user of any regret or pity of killing a human being.

Summary
First introduced as Shinobu's sacred Gear during their first encounter, it is explained that such sacred gear is one of the wickest and most evil there is, considered one of the biggest "Bug" of God's system.

Being a natural-born killer, however, Shinobu doesn't like her sacred gear, as it make her life as an assassin boring and monotone, despite claiming being a "killer that doesn't kill". The Sacred Gear soon is sealed from within her, so her urges can be controlled.

Appearance
The Sacred Gear manifests itself as a dragon-shaped half helmet with demonic horns sprouting from the side of the head and forehead, colored blue.

In it's Balance Breaker, it takes the shape of a gigantic UFO-like circle that hovers around the area, affecting everyone on it's reach.

Abilities
"I kill because I kill. I kill because I can, I kill because you know too much, I kill because I like you, I kill because I'm hungry, I kill because the movie I was looking forward to is close, I kill because my batteries are almost dead, I kill because the weather is lovely, I kill because a girl I hate tripped; I kill because tomorrow will rain, and I kill... Because there's no reason for me to kill."

- Akame Akira Considered one of the wickest sacred gears ever created, Cold Heart allows the user to cease all emotions and traumas regarding a kill. The User won't feel any regret, trauma, pity or any slightest amount of guilty in a kill, as it won't even reach his or her head as they cease a life. It can also shut the emotions down regarding death as a whole. However, people that has volatile killer instincts wil still search for death regardless, meaning the sacred gear cannot change the core of a personality as a whole. If this is exclusive of Shinobu or another bug, it is unknown.

Forms
In it's initial form, Cold Heart takes the shape of a horned half-helmet with demonic designs, and it can be forcibly activated in a situation where death will most likely accur.

Balance Breaker: Heart Eater
In it's Balance Breaker, Cold Heart takes the shape of a blood-red rune that hovers around a certain area, and allows the user and all under the reach of the rune to completely be devoided of emotions.

Trivia

 * The Sacred Gear is based on the concept of psychopathy, in which people fells no remorse to heinous acts.
 * According to Shinobu, Cold Heart can speak, hinting that the Sacred Gear may or may not have a spirit sealed inside of it.
 * Also according to Shinobu, Cold Heart doesn't need the urge to kill to be activated.