Hayate no Gotoku! Episode 10, title name as There's a Subtle High Deflation in the World. Play Games without Accumulation (世にも微妙なハイデフレ.ゲームは積まずにプレイしろ,Yo ni mo Bimyō na Haidefure. Gēmu wa Tsumazu ni Pureishiro?) aired on June 3rd 2007, the English Animax dub aired on June 24th 2009.
This episode takes place during the events of episode eight, and it shows previously unseen events that occurred during the day. Maria is seen singing in a music video, being watched by a group of bald men. Partly through the song, the television explodes. Meanwhile, Nagi is playing a game on an old video game console, with Sakuya present. Sakuya expresses her dislike of the game's simpler style, and Nagi responds mentioning that she's tired of more modern games. A mysterious santa enemy appears inside the game, swiftly defeating her character (who was named Hayate), and then the game starts to insult Sakuya and Nagi. The two respond by attacking the console. Maria enters the room and tells Nagi and Sakuya that the food is ready, and they leave the room. As they leave, the console starts to glow a dark aura. The next morning, Klaus starts yelling, announcing events and locations in the game. Nagi wakes up, and Maria tells her to get dressed so that she can go to school.
Nagi and Maria are then seen watching the show in the background, discussing the nature of their appearance. Sakuya barges in the room with the console to see the old video game possessed by a demon. She orders her butlers to destroy the demon, but they fail, and the demon starts to attack Sakuya and her butlers by flooding the room with takoyaki through the TV. Meanwhile, in the demon castle (which is just a small house on a tall column), the demon turns out to be a girl with a talking skull on her head, and she establishes herself as the final boss of the game. She waits for a hero to come, as if she defeats the hero, she would be free from the game. The demon then sets traps throughout the Sanzenin mansion, appearing as game controllers. However, most of the controllers get crushed. Outside the mansion, the three student council members come to visit Hayate, but Miki notices one of the game controllers, still intact. She picks it up, activating the demon's trap, and they are dragged into the video game world. The trio are then declared the heroes of the game, and a slime monster appears. Miki used Risa as a shield, causing the slime to attack and kill her. The slime then starts to attack the other two, using an attack that involves a ghostly head flying out of the slime, though the demon ends up saving them using an lightning attack to destroy the slime, though Izumi takes some damage from it. As Izumi, Miki, and a dead Risa (in a floating coffin) continue with their adventure, a clip shows Hayate in his catgirl outfit from episode eight singing. As the trio moves along, eventually Miki hears Risa talking inside the coffin, and she opens it up to find that she's currently using her phone and a fan, annoying both Miki and Izumi. Meanwhile, in the mansion, Isumi senses the presence of the demon, though she gets lost trying to find it and ends up at the bathhouse.
Before the second half starts, Nagi lists the top fortunes for the day on a television program, which is followed by a commercial for Wataru's video store. After the commercial finishes, the trio in the video game world is mentioned having found a village full of people they couldn't understand, though footage of Isumi taking a bath is shown. Back in the video game, Miki becomes fired up, and she throws her cellphone at the demon king's castle's pillar, and it appears to transform into a robot of some form. The phone returns to her, and then she uses it to call someone for assistance. Out of nowhere, Hinagiku appears behind the trio, and she asks them why are they in a video game. The demon decides to make Hinagiku and the trio to come to her tower in the sky, lowering a banner asking for them to come, and dropping equipment from the sky. As they prepare for the journey, Nagi starts reading fan mail, which tells of someone's surprise at Maria being 17 years old. Afterwards, Hinagiku and the trio, all equipped with various weapons and armor, finally meet the demon face to face, and she executes her final attack, though this just results in a pan being dropped on her head, defeating her and ending the game. The game's ending shows that the heroes defeated the demon and were sent back to their world, with their memories of the video game world lost. Before the end of the episode, Sakuya begins complaining about the ending, while she and Isumi are still stuck in the mess created by the demon king.
Before the opening credits it was noted by the Narrator and Maria that this episode was originally drafted by Kenjiro Hata.