As I'm sure you remember, we discussed and overwent the inner workings of the ability known as the Drain. It's a passive ability to drain the energy from a foe after maintaining contact with them, and sending it back to the Nekura to strengthen ourselves. Now, a major flaw in the Drain is that it only works on Sentient beings, living creatures. This means it can't take chakra from a jutsu or creation.
Another thing to note before we move forward is that though we all possess the same ability to manifest Keigoku and utilize the power of the Juubi, we all have a different beast inside us. We all have some form of dark emotion or craving that has made us the monster we are inside. When controlled, we are restrained, yet safer. When set free, we become our true selves....you see, when the Juubi's chakra latched onto Anshoku, it led to his inner beast becoming stirred and a part of it awakened after each usage of Keigoku. Feeling this each time, Anshoku sought out a way to find contact with this beast. He failed to do this initally, the closest he came was the creation of the Drain. He left his notes in several scrolls, and these scrolls passed down into my, Akuma's, possession. After studying them thoroughly, I created a way to make manifest those dark thoughts into a corporeal form, living and more dangerous as it is free.
The key concept behind the jutsu is that inner beast being released and through his connection to the user, can use the very ability Anshoku studied greatly. However, going deeper than the surface that Anshoku touched, I found that the best way to create this effect was to use that ability, the Drain, in a way to drain not humans, but chakra based attacks. By channeling great amounts of shape manipulation to it, you allow it to take form and it takes it's own mind, aimed at only protecting you and causing as much damage as possible.
The first step to doing this is by generating four large portals around you that Keigoku streams through and then wraps around you.
