Fics like Dearest Diary,

Noir, a primal demon, gets bored and decides to write a diary. With nothing else to do, writing the diary becomes part of his daily routine. Along the way, though, he notices a peculiar slime. Not knowing how important this slime would come to be someday, he takes simple note of him. TLDR Diablo's a fangirl.

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1. Snapshots by PongeSponge (転生したらスライムだった件 - 伏瀬 | Tensei Shitara Slime Datta Ken | That Time I Got Reincarnated as a Slime - Fuse)
2. Black Iris by Kaitou_Luminous (転生したらスライムだった件 - 伏瀬 | Tensei Shitara Slime Datta Ken | That Time I Got Reincarnated as a Slime - Fuse)
3. Dominant Run! by Greyninja27 (転生したらスライムだった件 - 伏瀬 | Tensei Shitara Slime Datta Ken | That Time I Got Reincarnated as a Slime - Fuse)
4. Skin to skin by athenaistired (転生したらスライムだった件 - 伏瀬 | Tensei Shitara Slime Datta Ken | That Time I Got Reincarnated as a Slime - Fuse)
5. Reborn as the first Nephilim by Lord_Lathiathen, RandomNote (転生したらスライムだった件 - 伏瀬 | Tensei Shitara Slime Datta Ken | That Time I Got Reincarnated as a Slime - Fuse, Other Fandoms To Be Added, more)
6. Scorching slime by FoofyFang (転生したらスライムだった件 - 伏瀬 | Tensei Shitara Slime Datta Ken | That Time I Got Reincarnated as a Slime - Fuse)
7. Re: across the land. by Decade112 (Re:ゼロから始める異世界生活 | Re:Zero Starting Life in Another World (Anime), 나 혼자만 레벨업 - 추공 | Solo Leveling | Only I Level Up - Chu-Gong, more)
8. The Consequences of Chaos by NiceApep (転生したらスライムだった件 - 伏瀬 | Tensei Shitara Slime Datta Ken | That Time I Got Reincarnated as a Slime - Fuse)
9. My Hero Tensura by AgentT123, RandomNon3859, WatcherMagic (僕のヒーローアカデミア | Boku no Hero Academia | My Hero Academia (Anime & Manga), 転生したらスライムだった件 - 伏瀬 | Tensei Shitara Slime Datta Ken | That Time I Got Reincarnated as a Slime - Fuse)
10. Quirks, Gourmet, Demigods, Dragons, Slimes and Aliens, Oh My by AliasEinzwerthos, AzemTheEverRecording, Darth_striker117, Orion_the_Omniversal_Watcher (僕のヒーローアカデミア | Boku no Hero Academia | My Hero Academia (Anime & Manga), Percy Jackson and the Olympians - Rick Riordan, more)
11. That Time I Reincarnated as a Gay Slime by Dragonify (転生したらスライムだった件 - 伏瀬 | Tensei Shitara Slime Datta Ken | That Time I Got Reincarnated as a Slime - Fuse)
12. Children of Tempest by Willsteredge (転生したらスライムだった件 - 伏瀬 | Tensei Shitara Slime Datta Ken | That Time I Got Reincarnated as a Slime - Fuse)
13. That Time I Was Reincarnated In Brockton Bay by nimodes (Parahumans Series - Wildbow, 転生したらスライムだった件 - 伏瀬 | Tensei Shitara Slime Datta Ken | That Time I Got Reincarnated as a Slime - Fuse)
14. i have loved you for a thousand years (i'll love you for a thousand more) by misslucy (転生したらスライムだった件 - 伏瀬 | Tensei Shitara Slime Datta Ken | That Time I Got Reincarnated as a Slime - Fuse)
15. Boku no Slime Academia! by via_the_cryptid (転生したらスライムだった件 - 伏瀬 | Tensei Shitara Slime Datta Ken | That Time I Got Reincarnated as a Slime - Fuse, 僕のヒーローアカデミア | Boku no Hero Academia | My Hero Academia)
16. Slime adventures and helping the true dragon's problem. by Hypertrixdark (転生したらスライムだった件 - 伏瀬 | Tensei Shitara Slime Datta Ken | That Time I Got Reincarnated as a Slime - Fuse, star war, more)
17. Shizu, Lord of Wisdom by Willsteredge (転生したらスライムだった件 - 伏瀬 | Tensei Shitara Slime Datta Ken | That Time I Got Reincarnated as a Slime - Fuse)
18. Bunch of Slimy One Shots by FoofyFang (転生したらスライムだった件 - 伏瀬 | Tensei Shitara Slime Datta Ken | That Time I Got Reincarnated as a Slime - Fuse)
19. I'm A Slime On The Move by KermieTheFroggie (僕のヒーローアカデミア | Boku no Hero Academia | My Hero Academia (Anime & Manga), 転生したらスライムだった件 - 伏瀬 | Tensei Shitara Slime Datta Ken | That Time I Got Reincarnated as a Slime - Fuse)
20. Rimuru, Princess of the Storms. by Critz (転生したらスライムだった件 - 伏瀬 | Tensei Shitara Slime Datta Ken | That Time I Got Reincarnated as a Slime - Fuse)