User blog comment:Jopjopjop/Volume 18 Spoilers/@comment-174.119.241.202-20140912164205/@comment-1359322-20140923005221

Maybe Cao Cao heads to the Underworld Prison to rescue his 2 captured allies and Euclid takes this opportunity to escape. Then Volume 20, would be focusing on capturing Euclid but not only did they fail, they even allow him to unseal the Malebranche. Well this is just my imagination ignore me.