Dream Dating Sim is a game jointly prepared by Dhampir and Sirens to wake up Laira, the Siren Empress, by getting her to fall in love. This is the game that plays out the main events of Volume 4 and 5.
- Each participating players shall wager everything they have.
- The scenario and environment in the game can be modified according to the participant's imagination.
- The player who managed to make Laira fall in love and wake her up wins.
- The player who get rejected or dumped by Laira loses.
- The loser shall be ejected from the game and pay his/her wager.
In Sora's version, the game was made into a dating sim based on a high school scenario. Each players are presented with a series of commands, including "gift", "date invitation", "confession", "magic (cheat)" and so on. The players may choose to do anything they like, including shopping or visiting nearby facilities.
Each "days" would start at the beginning of school hours, with unimportant activities like brushing up and breakfast skipped, only leaving fuzzy memories. The players may choose to join any school clubs (although everyone except Steph chose the Go Home Club), and there were also events like sports festivals happening in school. Laira will come to school every day.
800 years ago, after reading The Tale Of The Arrogant Princess, the then-princess Laira greatly emphasized with the titular character. She decided to go into hibernation in order wait for her "true love", who would then get everything she has.
Eventually, the former Siren empress died and Laira became the new empress, which put both Sirens and Dhampir into the crisis of extinction. In order to wake her up, they made use of Dhampir magic and made her dreams a dating game, so that someone could wake her up and resolve the crisis. According to the records found on Avant Heim, there were at least 19 attempts from 5 races before the events in Volume 4, but no one succeeded in doing so. Meanwhile, Sirens killed Dhampir males one by one during their reproduction, finally leaving only a single male left, which is Plum.
To save his own race from extinction, Plum went to 『 』 and seek out their help, stating that he has a sure-win cheat -- a love magic. 『 』 and Co. accepted the request and headed to Oceando. During the game, 『 』 and Co. were simply enjoying themselves with various activities, while Ino kowtowed in front of the school for 40 full days. Laira reached out to Ino and rejected him, in which he responded by activating the love magic. The magic worked, but Laira didn't wake up and Ino was declared a loser. Right at this moment, 『 』 and Co. left the game with Jibril's magic, and revealed that both Sirens and Dhampir had their own ulterior motives.『 』 and Co. saw through all the trickery, and were just there to gather evidences. The truth is no one knows the true conditions to wake up the Laira.
After figuring out the true conditions of winning, Sora, Shiro and Jibril reentered the game. This time, they made the game a living hell for Laira by turning it into a doomsday scenario, while hurling her tons of physical and verbal abuse. The plan worked and Laira woke up from her 800 years slumber, as it turns out that the love she was seeking is "unobtainable love" and the way to clear the game is to abuse her without falling in love with her.
- Sora based the game upon Tokimeki Memorial, a well-known Konami dating sim series. Even the official "Konami Man" cheat was mentioned.
- During the second act, the game was modelled upon ending B of the PS2 game Drakengard published by Square Enix, in which the humanity was destroyed.