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"Mist! Papyrus will die!"
– LanternDay Sans, proving that saying "Crap! Papyrus wants those!" in German can lead to misunderstandings,  language: German

LanternDay is an AU that is heavily based on German folklore, language and daily life.

Every monster speaks only German and while the basic plot is based on original Undertale, it was expanded / changed by the inclusion of German folklore and other things. Some of the underground's habitants have a changed design, too.

To battle the language barrier monsters like Sans are using a smartphone with a translation app.


Undertale Characters


The human child. They are bilingual and thus able to communicate with the monsters. Because this AU is heavily influenced by Germany and its language which needs genders for a working grammar[2], the child is a boy.


Sans is a 16 years old skeleton monster who strongly believes that he is actually a human called "Chance" who is wearing a magical skeleton costume. He loves to tease his brother Papyrus and his stepsister Fuku and his German puns tend to be suggestive. Unlike the other Sanses in the multiverse he is fairly active and has a helper syndrome. He avoids battles at all costs due to being a pacifist and unable to use any magic except for a masterful teleportation skill. Sans is extremely afraid of the darkness and always carries a lit(!) lantern in his body. Thanks to the language barrier he isn't very talkative when his smartphone is out of power, which happens a lot when he's travelling across the mostly english speaking multiverse.


Papyrus is 12 years old and fairly obsessed with bread. His biggest dream is to create spaghetti bread. Thanks to the underground TV's lax handling of nudity[3], he barely bats an eye when something suggestive happens around him. But this doesn't mean that he isn't a very naive kid, all in all he is still basically like any other Papyrus


Undyne is one the few monsters in the underground who isn't a pacifist. She loves to create creative magical lanterns that can aid her during battles.


Grillby is the foster father of Sans and Papyrus and the biological father of Fuku. Being a single dad he can be fairly protective of his children and a little bit too forgiving. He rarely talks.


Fuku is Sans and Papyrus' 12 years old step sister. She is fairly talkative, helpful and loves to tease her step brothers.


Alphys is the royal scientist, able to speak English and German and a huge anime nerd and cosplayer. Sometimes she argues with So Sorry and Mettaton if dubbed animes are better than subbed animes. She prefers subbed animes and shows in their original language.


Mettaton is Alphys' best friend and assistant. While he isn't that much interested in animes he likes to watch dubbed shows and cartoons.


Toriel is the former queen of the underground, wearing a blue coat. When she found the freezing human boy Frisk one year ago, she split her warm coat to share it with him. She likes to make caramel-cinnamon cakes.


Asgore is the king of the underground, wearing a red coat. He likes to drink cornflower tea and carries a huge sword.


Asriel was Toriel's and Asgore's child, wearing a purple coat. When he met the first fallen child Chara many, many years ago, he shared his coat with them. His selfmade lanterns had a tedency to fall apart easily.


Flowey is a speaking blue cornflower. He is able to make the tips of his "antennas" glow. If you fall for his false friendlyness and come too close to him he gets sharp teeth and red glowing eyes.



  • The legend about the "lost soul" is based on the Martinstag (St. Martin's Day[4]), a German tradition.
  • Flowey is a blue cornflower, which was one of the national symbols of Germany.
  • Mettaton's square body is based on the Z3, the world's first working programmable, fully automatic digital computer, designed by German inventor Konrad Zuse.
  • The design of the clothes of Frisk, Sans and Papyrus are all based on the European flag and the German flag.
  • Sans' smartphone charger has a so-called Europlug and thus only works with fitting sockets.
  • Papyrus and Muffet are obsessed with bread, which is based on the fact that Germany produces more varieties of breads than any other country.[5]
  • Papyrus and Sans are both fans of soccer, the most popular sport in Germany.[6]