In the 9th event, Maple and the 【Maple Leaf】 members showcase their overwhelming presence as they begin exploring the submerged city on the 8th floor! Sari demonstrates her exceptional 【Diving】 skills, tackling the sunken ruins solo and surprisingly obtaining the second unique series equipment. Meanwhile, Maple struggles with the unfamiliar underwater exploration but enjoys the 8th floor with Iz's special jet ski and enhanced diving suit! When she tries to coordinate with Sari, who has acquired new equipment, they unexpectedly discover a rare item deep underwater, leading to a surprising new skill──. In the sky, on land, and now underwater──?! The 12th installment of the series advancing with the ultimate defense!