As an invisible man enters the mansion to assassinate Hime, she goes wild with a chainsaw chasing him, but to no luck. After the invisible man covers the hallways with invisible threads, Hiro gets caught by these traps, but Hime and Flandre manage to save him. With his life force fading and needing restoration, Hiro slowly comes to realize that he has no choice but to be involved with Hime. After injuring the invisible man and following him into the basement, Hime eventually sets the mansion on fire. The invisible man tries to escape from the mansion, but Hime is able to slash him when seeing him on fire.

Hime, Hiro, and Flandre, with Riza in tow, travel to Hime's lake resort to relax. At night, their resort is suddenly pulled down into the lake, which has them evacuate the area. They are surrounded and then captured by a race of mermen who are after Hime's immortality powers. When a giant merman named Poseidon challenges Hime to a duel, Riza steps in and accept the challenge in her place. Although Riza struggles as she fights Poseidon, a full moon appears in the sky, giving her the strength to defeat him. The next day, Riza declares her intention to stick close to Hime in order to find an opportunity to take her revenge on one of Hime's siblings, the one responsible for making Wildman betray Hime.