The ability annuls the skills of anyone he touches. Furthermore, the ability relies on skin contact and is always active. As such, he can nullify any ability even while restrained as soon and as long as it touches him. Due to this specific condition, the ability also apparently nullifies Akiko Yosano's healing ability; hence, Dazai requires the standard medical procedure or operation whenever he gets injured, unlike his fellow Armed Detective Agency members whom Yosano typically heals using her ability.
Dazai considers No Longer Human to be absolutely effective on any ability, so it cannot nullify any form of power that is not considered an "ability". As a result, Dazai cannot nullify Ranpo Edogawa's deduction skill and Howard Phillips Lovecraft's eldritch form, both of which are therefore not considered as abilities.
Thus far, Dazai has nullified the following abilities:
- Upon the Tainted Sorrow
- The Matchless Poet
- Unnamed number ability
- Beast Beneath the Moonlight
- Dogra Magra
- The Grapes of Wrath
The ability is based on the real-life Osamu Dazai's novel entitled No Longer Human (人間失格, Ningen Shikkaku?, literally "Human Disqualification"), which tells the tale of Yōzō Ōba, a troubled man incapable of revealing his true self to others out of his detachment and fear toward human interactions, hence deeming himself disqualified from being human. He instead maintains a facade of hollow jocularity, but his alienation remains despite his efforts to alleviate his internal suffering. Within three memoranda that chronicle his early childhood through adulthood, Yōzō writes about life's casual cruelties, as well as its ephemeral moments of human connection and tenderness.