[OPTIONAL] During Chapter 2, there is a sidequest to summon a demon for Eleni. You can trigger this by going into her house, talking to her, and collecting the things she asks for. You will need Moxie with you to be able to collect everything, but don't go to Treat's house without summoning the demon first. Once you do, you'll be able to read the books on Eleni's shelf. This is where you learn the code "C N D".

Play through Chapter 3 until you reach the room behind the fireplace. Once the lights are on, you can open the safe with the combination you learned in Chapter 2 (this is what makes Step 1 optional). The safe contains the Anywhere Pass, which will be essential for reaching the Netherworld later.

Play through Chapter 4 until you reach Frosting. Head to the gate south of Frosting (where you can look out and see the witch town). Lemonne will give you Devipuri if you keep talking to her.

Return to the train station. On the left side, there is a gap in the trees where you can find Moxie in a tent. She will give you the Anywhere Pass in exchange for the Devipuri.

Now you can use the train to go to the Netherworld! Explore until you find BAD END THEATER, then go inside and talk to the witches there. Lilium will ask if you're interested in seeing the bad endings... if you say no, you'll be blocked from continuing this side quest, so be sure to say yes.

SAVE YOUR GAME, then exit to the title screen. You can now skip to Chapter 8 from chapter select. Play through it normally until you reach Krem--if you have an existing chapter 8 save file in Krem, it's safe to load that as well.

Off to the right of the fountain, there is a train station. If you try to buy a Ticket to the Netherworld, the Anywhere Pass will appear instead. Return to BAD END THEATER and save your game once more. From here, Lilium will give you the instructions to get the different bad ends.

Continue to the end of Chapter 4. There's a prompt to return Moxie's Anywhere Pass if you talk to her again, but DON'T DO THAT! You still need it. Skip through the rest of the game until you get to Krem in Chapter 8.

Off to the right of the fountain, there is a train station. Finally, you can get back to the Netherworld and enter the theater again! Once inside, save your game. From here, Lilium will give you the instructions to get the different bad ends.