Dogi✩Maji✩Memorium (Dogi Maji in short) is a series of RPG school dating sims where anyone who registers is pulled into the game world. (note: If you die in the game, you die for real). To leave the game, you have to win it.
The game is set in a fictional school, which seems to be in the human world. It has computer-generated classmates and teachers whom with the players of the game can interact.
The games are played on Gehenna Station, which could be a parody of the PlayStation. The games are also likely a parody of the Tokimeki Memorial dating sim series.
Note: this section may include spoilers
In Lesson 10, Mammon wishes to make Lucifer and Satan get along again after their fight, so he has the idea to register Satan and Lucifer in the game to make them work together in order to get out of it. Leviathan helps Mammon in registering them but also registers himself, Mammon, and MC as well. MC is registered as the heroine (a title unrelated to MC's actual gender) and the other players, Lucifer, Mammon, Levi, and Satan must work to increase their favorability with the heroine in order to beat the game. The game can only be won if MC as the heroine receives a confession of love on the Roof of Legend that they then accept. It is rumored that if two people confess their love on the Roof of Legend on Graduation Day and become an official couple, then they'll live happily ever after together.
The majority of the game involves the characters attending classes while they attempt to raise their favorability score with the heroine. On Graduation Day, the characters prepare to profess their love to the heroine, however, on that day, the game takes a twist and becomes a survival horror game. Monsters show up and begin to devour the NPC classmates. One of their classmates is called John and he sacrificed himself to save the group. Levi says that he looked like the kind of guy who would die at some point during the game. The group learns from John that there will be a Final Battle coming up soon. MC, Mammon, Levi, Lucifer, and Satan manage to escape to the Roof of Legend and this is where they meet the final boss of the game, who turns out to be Cerberus. Lucifer is able to defeat Cerberus which allows the group to complete the game and return to the real world. Levi says that they broke the RTA speedrun record and leaves the game a 5-star review, specifically praising the ending.
Dogi☆Maji 2 is the sequel game and its plot is told through a series of chats. In Dogi✩Maji 2: The Reckoning 1-2, Leviathan purchases the game and makes Asmodeus, Beelzebub, and Belphegor play it with him. He also requests MC to play the heroine again. Once this group completes the game, Levi excitedly announces that they have a new speedrun record and notes that the final boss was the same as the first game. He also praises the developers for upping the difficulty and for the amount of content they added. Asmo also seems to have enjoyed the game, however, Beel and Belphie did not. Belphegor complains that the game requires an intimacy level of over 99 to avoid the bad ending. This is a different mechanic than in the first game where intimacy scores didn't matter.
In the chat A Regular Thing?, Raphael plays Dogi☆Maji 2 with Leviathan, Thirteen, Mephistopheles, and MC. In their playthrough, Mephistopheles was the heroine and it is specifically mentioned that the story only continues when the heroine's intimacy level reaches a certain level. The final boss for their playthrough was Henry 1.0.
Dogi☆Maji 3 is played in Leviathan's 2021 birthday event. The brothers knew that Leviathan wanted to play it so they did their best to find a copy for him before his birthday, even though the game's official release was scheduled shortly after Levi's birthday. Satan managed to obtain the beta version, however as this version of the game is unfinished, it contained many bugs. These bugs took the form of Little D. No. 3 and caused issues for the group while playing. One such issue is that Levi and MC essentially ended up switching bodies because their data got corrupted. However, they discovered that while inside the game, they could enter battles with the Little D. No. 3's and defeating the Little D's would act as the debugging process which meant the errors in the code would be corrected. At the end of the event, Levi tells MC that the release of the game has been delayed. The announcement did not say why but Levi guesses that it was due to the amount of bugs, particularly because the corruption of the heroine's code seemed to be a fundamental system error as opposed to a simple bug.
In this event, it was said that the game's tagline is "Relive the nervous excitement of falling in love for the first time!"
- In a :D Jobs cutscene at Hocus Pocus, Leviathan tells Mammon that Version 2.10 of the game has a bug that crashes the whole game so the batch was recalled. As a result, this version is exceedingly rare.