Volume 9 is scheduled to be released on August 15, 2018.
The limited edition will be bundled with fifth drama CD titled "1st Yaichi Kuzuryuu Ryuuou Title Defense Commemorative Tournament".
The Bonus Track is titled "Ai-chan's Yandere Level Check".
The Drama CD will feature Yaichi, both of his disciples, Ginko, Keika, the JS-ken members, Asuka, and Ika.
Source:
https://www.amazon.co.jp/dp/4797396261
Also loli Ryou and Machi