What's the name of the battle theme used in Big Order? I was watching Big Order recently, and when I looked it up I could easily find the op, but I couldn't find that really awesome battle theme. It comes on IIRC once or twice per episode, and usually at the climax of the episode.

So, does anyone know its name?

I'm pretty sure it's in all of the episodes, but for a specific example, take the latest episode (ep 6). It's in most of the underwater scene, from around minute 20.
https://www.youtube.com/watch?v=HS7fh_QD6sw#t=33m40s starting 33:40

It's called "决着！"