A technique that in which the blood is compressed and condensed to its limit between the palms of user. Then, compressed blood sphere can be used to perform an extension technique. Because it requires time to apply Convergence to blood, user is vulnerable against fast and quick attacks.
Noritoshi Kamo used this to utilize its extension technique against Hanami. Thanks to Toge Inumaki`s Cursed Speech, the special grade cursed spirit is immobilized for a period of time which allowed Noritoshi to bypass the time requirement to charge the Piercing Blood technique.
Kamo is also capable of condensing a larger amount of blood for a more devastating attack. He used a blood bag to charge a Piercing Blood technique powerful enough to damage Naoya Zenin's Cursed Womb form.
Choso, thanks to his half-cursed spirit half-human physiology can use this technique repetitively without exhausting himself. It is one of Choso's most used techniques as it is key charging up his most powerful attacks. He can keep condensed blood sphere around him and manipulate them as he wishes to activate its extension techniques. He is able to use Piercing Blood which is the strongest known technique of Blood Manipulation and also Supernova which is invented by himself.
There is a traditional stance for activating Convergence but Choso has used other ways to cast it as well. Choso has also used the stance as a feint to trick opponents into thinking he's about to fire Piercing Blood. Thanks to this versatility he have, he was able to defeat Naoya Zenin who has knowledge on Blood Manipulation and its extension techniques.