She arrives at the place where the letter invited her, and everything suddenly goes black. When the lights return, she notices that the sky has become purple, and her magical guardian isn't present. Another magical girl arrives and informs the protagonist that this is a space only magical girls could enter. The mysterious girl then starts to cast a spell, and regardless of what the player does, she succeeds at casting it. The player gets a game over screen, but don't be fooled: you just have to start the game again.
Everything starts with the protagonist having a conversation with her magical guardian yet again... until she starts to feel like they already had this exact conversation before.
a letter of challenge provides examples of:
- Fission Mailed: After the mysterious girl casts her spell, the player gets a game over screen. However, starting again will continue the story, as there is a time loop.
- "Groundhog Day" Loop: Every time the mysterious girl casts her spell, time resets back to when the protagonist was returning from school, right before she found the letter.
- Leaning on the Fourth Wall: If you repeatedly perform an action that failed in one of the previous time loops, the protagonist will question why she keeps doing something so useless and say that it's almost as if someone is forcing her.
- Minimalist Cast: Besides the protagonist, her magical guardian, and her rival magical girl, no character ever appears onscreen.
- Nameless Narrative: No character in the story has a name. The game's antagonist is usually referred to as "the mysterious girl."
- Poor Communication Kills: The mysterious girl wants to befriend the protagonist, so she summons her with a letter and creates a barrier only magical girls could enter to talk to her. The protagonist ends up thinking that the mysterious girl wants to fight her. The mysterious girl, instead of simply explaining her intentions, turns back time, as she feels like she has messed up her only chance to talk to the protagonist. Had the mysterious girl simply explained that she wanted to be friends instead of turning back time, the entire conflict could've been avoided.
- Puzzle Boss: It's impossible to defeat the mysterious girl by fighting her, as the player doesn't have enough turns before she casts her spell and resets time. Rather, she is defeated by the player doing nothing for a certain amount of time, resulting in them skipping a turn. However, this doesn't become an option until the last time loop.
- Waiting Puzzle: In the last time loop, the player doing nothing for a certain amount of time results in them skipping a turn. Doing it multiple times will lead to the mysterious girl finally talking and explaining her motivations, as she now understands that the protagonist doesn't want to fight.