A Crossover Anime/manga Series, But in NPC Mode

[Day 1: I, Lynn, 18 years old, am a transmigrator.] [Good news: I transmigrated to a crossover anime world, and my deskmate is none other than the background heroine, Kato Megumi.] [Bad news: Everyone except me seems like an NPC in a game.] [Something's wrong with this world.] [Day 2: Senpai's black stockings are so lustrous!] [Day 3: Yukino's over-the-knee socks are amazing!] [Day 4: With a figure like Yui's, how could Hachiman refuse?] [Day 5: Eriri is so flat-chested, not as good as Yukino.] [Day 6: Damn it, I need to pull myself together and find a way to change this boring world! A true man can't be swayed by beauty!] [Day 7: I saw Kato Megumi first, and now it's only her turn? Typical background heroine.] [...] [Day 30: Wait, it seems like Utaha-senpai is alive?]