Harmlessness

Harmlessness(無害; Mugai), also known as True Neutrality(完全中立性; Kanzen chūritsu-sei), is an innate ability in DxD: Twice, said to be the complete opposite of Killing Intent. By cleaning one's mind and having a unshaken heart, one is able to become a 'complete harmless being'.

Summary
This strange, metaphorical ability was first mentioned during the events of Volume 1. Asked to par with the next heir of the Phenex clan, Red Phenex, Takumi has shown the uncanny talent to avoid both magical and physical assault coming from the former, winning by default as Red succumbed to exhaustation, even himself becoming

It is later discussed and comfirmed by both Kunou and Lilith that Takumi possesses a strange ability that reflects his calm, harmless, trouble-avoiding nature, which isn't derived from any form of prior magical sense such as senjutsu or devil magic, and it's his own talent for such, being an 'unlucky person'.

Abilities
Harmlessness is an exclusive metaphysical ability which allows the user to become a completely 'harmless person'. Said to be the complete opposite to Killing Intent, harmlessness needs the user to both clear his/her mind and absolutely want no harm done to others.

With that, one becomes a complete harmless person, being unable to harm others, while at the same time being unable to be harmed. By wanting no harm to befall others and with the will to avoid trouble, one becomes more prone in dodging skills and excessive luck in avoid traps or disadvantaged situations. Another more passive ability is to become so 'harmless', one can blend into the environment with ease without assistance, hiding everything except their optical presence, as well as becoming stealth masters.

Drawbacks
Since one has to become a harmless person, the user must remain calm and passive as possible, as any form of disturbance will neglect the ability as a whole. Also, the user becomes complete harmless, and won't be able to harm others.

Trivia

 * This ability is vaguely based on the Shield Hero series.