Shunkō (瞬閧, Flash War Cry) is an advanced battle technique which combines the physical techniques of Hakuda with the spell-based techniques of Kidō.
Shunkō is the highest form of Hakuda technique. It comes in elements such as 'wind' or 'lightning'. It is an ultra-powerful technique in which one drives Kidō into one's arms and legs. The Kidō itself can be controlled and fired at opponents from the body. Shunkō was first used by Captain Suì-Fēng in her fight against her old master, Yoruichi Shihōin. Suì-Fēng states she invented the technique of combining Kidō and Hakuda so recently she had no experience with it in battle, let alone enough time to give it a name. Yoruichi, however, reveals Shunkō is the technique's name, and she invented and learned the ability long before Suì-Fēng. The keisen uniform has no back or sleeves because the fabric will rip apart when the user's back and arms are filled with Kidō. Though Yoruichi's Shunkō is perfected, she still has difficulties controlling it. The uniform worn when punishment is carried out is specifically geared for Shunkō. By concentrating Shunkō around a particular area of their body, a practitioner can prevent attacks from damaging or piercing this area.
Mukyū Shunkō (無窮 瞬閧, Tireless Flash War Cry; Viz "Infinite Shunkō")
Suì-Fēng would go on to complete her version of the technique after her fight with Yoruichi. She discovered a technique for making the Reiatsu she emits revolve around her like a vortex indefinitely, allowing her to maintain her Shunkō for as long as she wishes once she activates it.
Shunkō: Raijin Senkei (瞬閧 雷神戦形, Flash War Cry: Thunder God War Form; Viz "God of Thunder Battle Form")
Gaining a circle of electrical energy in the shape of Raijin's drums attached to her back as her bangs rise to form horns, Yoruichi unleashes a giant column of concentrated electrical energy to engulf her opponent.
Shunkō: Bakuen Musō (瞬閧 爆炎無双, Flash War Cry: Exploding Flames Unparalleled; Viz "Unrivaled Explosive Flame")
The pressurized Kidō emitted from Yūshirō's back creates a large explosion of concentrated energy, which engulfs his opponent and heavily damages them.
Shunkō: Raiju Senkei: Shunryū Kokubyō Senkei (瞬閧 雷獣戦形 瞬窿黒猫戦姫, Flash War Cry: Thunder Beast Battle Form: Flash God Black Cat Warrior Princess; Viz "Thunderous Black Cat Battle Princess")
Yoruichi's arms and legs are surrounded by electrical energy that takes the shape of claws. The electrical energy also manifests itself around Yoruichi's tongue, ears, hair, and backside. Her moodiness is significantly increased, causing her Reiatsu to change 48 times per second. She also cannot understand human speech.