I Kept Pressing the 100-Million-Year Button and Came Out on Top, Vol. 7 (manga) — Syuichi Tsukishima

Lia is captured by the Obsidian Order, and Allen and his friends must do everything they can to save her. With the timer ticking down on them, they finally find their way into the enemy’s base, but more daunting trials await them inside. Facing off against the strongest swordsman in history, will Allen fold to the pressure, or will he awaken to even greater heights?!