Fics like The 100 Girlfriends:Serendipity

Serendipity:The occurrence and development of events by chance in a happy or beneficial way. The biggest polyamorous relationship in the world has garnered two new followers. Meet Noroji Teku and Ami Hama, two girls from Kusuri and Kishika's class, as they get caught in the fun ensuing chaos that is Rentarou's Family.

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1. One-Shot Advent Calendar by namichwan57 (Bleach, Chainsaw Man (Anime), more)
2. Cutting The Chains by BrineBuster (君のことが大大大大大好きな100人の彼女 | Kimi no Koto ga Dai Dai Dai Dai Daisuki na 100-nin no Kanojo (Manga), 君のことが大大大大大好きな100人の彼女 | Kimi no Koto ga Dai Dai Dai Dai Daisuki na 100-nin no Kanojo (Anime))
3. My Big Brother And The Girlfriends Who Really, Really, Really, Really, REALLY Love Him! by NullSage975 (君のことが大大大大大好きな100人の彼女 | Kimi no Koto ga Dai Dai Dai Dai Daisuki na 100-nin no Kanojo (Manga))
4. Watching from the Afterlife: The 100 Girlfriends who found each other. by Magicfoxwrites (君のことが大大大大大好きな100人の彼女 | Kimi no Koto ga Dai Dai Dai Dai Daisuki na 100-nin no Kanojo (Manga))
5. The chosen and his seven soulmate by Derrickking (Pocket Monsters | Pokemon - All Media Types, 君のことが大大大大大好きな100人の彼女 | Kimi no Koto ga Dai Dai Dai Dai Daisuki na 100-nin no Kanojo (Manga))
6. Askbox - Potion Troubles by M4typewriter (Fate/Grand Order, Fate/stay night & Related Fandoms, more)
7. The 100 Boyfriends Who Really Really Really Really Really Love You Too by SneakyMcSneakerson (君のことが大大大大大好きな100人の彼女 | Kimi no Koto ga Dai Dai Dai Dai Daisuki na 100-nin no Kanojo (Anime), 君のことが大大大大大好きな100人の彼女 | Kimi no Koto ga Dai Dai Dai Dai Daisuki na 100-nin no Kanojo (Manga))
8. A middle-aged man has been transported to another world, but he will speedrun this Isekai adventure to see his daughter’s smile again by Kasu251 (君のことが大大大大大好きな100人の彼女 | Kimi no Koto ga Dai Dai Dai Dai Daisuki na 100-nin no Kanojo (Manga))
9. Hyakkano: Future by HyakkanoWriting (君のことが大大大大大好きな100人の彼女 | Kimi no Koto ga Dai Dai Dai Dai Daisuki na 100-nin no Kanojo (Manga))
10. The 100 Girlfriends Who Really Really Really Really Really Love Deku!~ by Brypops (僕のヒーローアカデミア | Boku no Hero Academia | My Hero Academia, 君のことが大大大大大好きな100人の彼女 | Kimi no Koto ga Dai Dai Dai Dai Daisuki na 100-nin no Kanojo (Manga))
11. Just a Gal Trying To Get Bi by sleepytiredhonkshoo (君のことが大大大大大好きな100人の彼女 | Kimi no Koto ga Dai Dai Dai Dai Daisuki na 100-nin no Kanojo (Manga))
12. It's a Free-Use Crossover Isekai Ask-Box!!! by Piswhack (ジョジョの奇妙な冒険 | JoJo no Kimyou na Bouken | JoJo's Bizarre Adventure, Persona 5, more)
13. A NNN Askbox by M4typewriter (Multi-Fandom, Snowbreak: Containment Zone (Video Game), more)
14. welcome to multiversal chat by orphan_account (Dangan Ronpa Series, 僕のヒーローアカデミア | Boku no Hero Academia | My Hero Academia (Anime & Manga), more)
15. Still Better than Black Keys by OverMaster (Fate/stay night & Related Fandoms, 英雄＊戦姫 | Eiyuu Senki: The World Conquest, more)
16. The 100 girlfriends who will NTR You by Kuroi_Survivor (君のことが大大大大大好きな100人の彼女 | Kimi no Koto ga Dai Dai Dai Dai Daisuki na 100-nin no Kanojo (Manga), 君のことが大大大大大好きな100人の彼女 | Kimi no Koto ga Dai Dai Dai Dai Daisuki na 100-nin no Kanojo (Anime))
17. The Two Girlfriends Who Really Really Really Really Really Love Each Other by Masshi (君のことが大大大大大好きな100人の彼女 | Kimi no Koto ga Dai Dai Dai Dai Daisuki na 100-nin no Kanojo (Manga))
18. 100GF What If: It WAS Reversi (V1) by ViViHarmonia64 (君のことが大大大大大好きな100人の彼女 | Kimi no Koto ga Dai Dai Dai Dai Daisuki na 100-nin no Kanojo (Manga), 君のことが大大大大大好きな100人の彼女 | Kimi no Koto ga Dai Dai Dai Dai Daisuki na 100-nin no Kanojo (Anime))
19. Femboifu-Inspired Oneshots (Naruto (Anime & Manga), この素晴らしい世界に祝福を! | KonoSuba: God's Blessing on this Wonderful World! - All Media Types, more)
20. Karane and Hakari: Three As One by Reidx00 (君のことが大大大大大好きな100人の彼女 | Kimi no Koto ga Dai Dai Dai Dai Daisuki na 100-nin no Kanojo (Manga))