It's true, I asked her in that tweet but she didn't want to give details. Neither Asakura via email.
I discovered that on the track
"End of a Vicious Struggle" it can be hear a guitar at the end, what makes me think of Kiyotsugu Amano. That piece from the credits could be one of the Asakura's, BUT the guitar segment it's not included in the length of the piece and I don't know where it comes from.
Edit: Nah, it's just a suscribe jingle from Ubi Sunt Music.