Ratio Technique (十劃呪法 Tookaku Juhō?) is Kento Nanami's innate technique. It grants him the ability to divide his target with lines and forcibly create a weak spot at the ratio point of seven to three.
The user of this technique can mark their target's body with lines divided into tenths. If the user is able to strike one of these lines on exactly the seven-to-three ratio point, they deliver a critical hit to the subject. This allows them to deal significant damage on tougher adversaries and cleave weak opponent's in two in a single hit.
The lines don't have to measure up to the target's full length or wingspan. Their head, torso, biceps, and forearms are all among applicable limbs for division. This technique can be used on inanimate objects in addition to living beings.
Kento Nanami honed his innate technique to a masterful degree while working as a grade 1 sorcerer. He usually used it in tandem with his blunt sword, but could activate it while fighting with his fists as well.
With his cursed technique activated on weaker targets like transfigured humans, Nanami can easily slice them apart with his blunt sword despite the dull edge. On the roof of Kinema Cinema, Nanami divulged his technique and performed it for Yuji, instantly slicing all the limbs off a transfigured human.
Against Mahito, Nanami first used his technique to break the special grade curse's arm. Mahito believed he reinforced his guard with cursed energy, but the critical hit still shattered his arm. However, Mahito's Idle Transfiguration allows him to reshape his own soul and regenerate wounds in seconds. Additionally, Nanami is at a disadvantage when Mahito transfigures his miniature humans into long-ranged attacks. He openly admitted to himself that Mahito's innate technique is a bad matchup for his own.
Nanami planned accordingly in the jujutsu battle and divulged the specifics of his Ratio Technique to Mahito. On top of his "Overtime" binding vow, this increased Nanami's cursed energy output exponentially. His enhanced abilities allowed Nanami to unleash Ratio Technique: Collapse, an extension technique that can be applied to a wide area rather than just a single target. By destroying the underground battlefield using Collapse and trapping Mahito under the rubble, Nanami was able to escape with his life intact. Following this encounter, Mahito nicknamed Nanami the "7:3 Sorcerer".
While fighting alongside Yuji, who can hurt the Mahito's soul directly, Nanami admitted openly his attacks didn't work on Mahito but added that he could still stifle the curse's movements. Working together, Nanami was able to immobilize Mahito with delivering critical hits while Yuji to landed attacks and dealt damage to his soul.
During the Shibuya Incident, Nanami dominated the curse user, Haruta Shigemo in their fight by creating weak points on his body and striking them with cursed energy enhanced punches. A simple backhand was enough to send Shigemo flying across the room and broke his nose. Shigemo admitted this attack would have killed him if not for his cursed technique. Nanami's third and final punch sent Shigemo crashing through a wall, utterly defeating him and smashing his face in the process.