Chikyuu Bouei Kazoku Special
English name: The Daichis: Earth's Defence Family - Into the Depths of Marital Hell
Genres: Action, Drama
Type: Special, Episodes: 1
Aired: Nov 25, 2002
Source: Original
Rating: PG-13 - Teens 13 or older
Synopsis:
An alternative episode 11 (or episode 11.5) released on the DVD set of Chikyuu Bouei Kazoku. 

The world's first experience simulation game park "Amber Crystal" opened in Chiba Prefecture. Opening day only allows couples inside with a special ticket. Seiko and cameraman Hayakawa, Mamoru and Junko-sensei are there to meet up. While saying "because it is a game, it's okay to do anything", Mamoru guards as a knight figure to raise XP to steadily power up. Meanwhile, Seiko who became a mage, realized that this game park is the invasion of the space monster and goes on to approach the final boss of the game.