Isn't it Beautiful? 
is a Katekyō Hitman Reborn! by esquitor is a mostly gen-fic series wherein Sawada Tsunayoshi finds himself pulled into the Underworld as a part of someone else’s Inheritance Plots and Plans, and decides he’s… well. Sorta okay with it. He’s okay with a lot of things. Aaaaabsolutely dandy about it.
Doesn’t mean he’s going to make it easy for them, though.
More Detail can be found at the wiki
As Summarized by the Author: The series is set in an Alternate Universe that is far more entrenched in flames than canon. Namimori and Kokuyo are towns on an island named Kakishima, and the Underworld starts spilling just a little bit Overworld. The main piece will be mostly Gen, save for the occasional brutal violence and any criminal reference that slips in. Any explicit content will be delegated to side-pieces. Will have some pairings, but doesn’t focus on romance. Hopefully.
Contain humor, some mystery, lots and LOTS of worldbuilding since it’s AU, a lot of throwback to actual Real Life criminal societies and cultural histories, and what I hope will be criminal masterminds. Themes include disabilities, LGBTQ themes, tackling the topic of peer abuse, a hot pot of cultures (so far we have the usual Japanese, Korean and Vietnamese/French immigrants, eventual 1st and 2nd gen), regimented conditioning of adults and children, a large amount of adopted individuals, and some insight into isolationist worldviews. Oh and also sci-fi. Flames and sci-fi.
Tropes:
- Abusive Parents: averted by Nana Sawada from canon. However, Iemitsu could be defined as this by neglect. It's complicated by the fact that he can invite others but is effectively blacklisted by the island authorities.
- Absurdly Powerful Student Council: As Reborn puts it, they're mostly organized student gangs given license over a certain area by the authorities, and patrolling is thinly veiled gang violence.
- A Child Shall Lead Them: What the Vongola wants to do with Tsuna. And Tsuna would not be happy with it once Reborn actually reveals what he is here for.
- Authority Equals Asskicking: Hibari against a group of Azayakatani
- The boy is a whirlwind, swinging his tonfa with ease and comfort and using them in probably unconventional ways. He hits with them, sure, and blocks, and parries. And then reverses his grip, uses the short handle to hook under the armpit or around a knee to trip them over. And then turns them around again to use as stilts for his hands, adding inches to the reach of his upwards kick that sends a far-taller opponent reeling back.
- Bunny-Ears Lawyer: Between the costume changes, the carrot/cake sweater and the Devil May Care attitude that Reborn has directed towards the rest of Vongola, one must remember that he is the World's Greatest Hitman. Even if he touches your leg with his sweaty skin.
- Cliffhanger: The author does this to the pain of the reader in Chapter 13. Why Reborn, why?
- In retrospect, it was probably a bad idea to shoot him in front of his friends. But the end results were well worth an angry Leon and a broken nose.
- Consummate Liar: What [Reborn] also has is the tendency to be a filthy, filthy liar. Reborn deceives Tsuna into thinking he's to protect, rather than to train him.
- Cool Old Guy: Reborn. Hana appreciates it before she finds out his real age. Then, it's Squick.
- Cuddle Bug: Tsuna does so during Collective Resting Hour.
- Curb-Stomp Battle: How Reborn dealt with the squad after finally igniting Tsuna's Dying Will Flames. Took thirteen chapters though.
- Deadpan Snarker: Nagi is great. Everyone here is spectacular. It warms the dead corners of Reborn's heart.
- Demonic Possession: Nagi and Mukuro, though it's more of a telepathic confession. Also, Kokuyo Guardian/Daemon Spade. Nicola Airo also experiences this when she attempts to land in Kakishima.
- Doorstopper: 145,596 words by chapter 14 for the main storyline. And let's not include the other stories in this universe...
- Fish out of Water: Reborn in Kakishima. When shopping for clothes in Kakishima as an adult, he cannot find good Italian style clothing.
- For Want Of A Nail:
- What if Namimori is situated in a semi-independent island?
- Rather than sneaking off to strengthen Vongola, Daemon Spade travels to Japan together with the rest of the Guardians in hopes of strengthening Vongola through a different way?
- Hitman with a Heart: Reborn finds himself growing closer to Tsuna.
- I Have Many Names: Reborn/Renato/ Rinaldo Salucci.. There are bets ongoing as to what his real name is.
- Immortality: What happened to Fon. And the rest of the Arcobaleno, given that Reborn is old and salty about it ten years back.
- Informed Ability: Reborn's the Greatest Hitman in the World. What else can you say?
- Justified Criminal: Reborn meets the Vongola after shooting his handler for money. It doesn't stop there.
- Known Only by Their Nickname: As a result of the above, Reborn is known only by his hitman name.
- The Lancer: What Mochida is shaping up to be.
- Last-Name Basis: Tsuna with Mochida
- Like Brother and Sister: Reborn and Hedda.
- The Mafia: The Vongola.
- Magic A Is Magic A: Reborn and Kakishima's parents compare notes on Sky Harmonization.
- Manipulative Bastard: Reborn. Just, Reborn. Daemon Spade and the Oyster Authorities. Who wipes out the memories of the previous mayor?
- Memory-Wiping Crew: Well, not quite Memory Wiping. Maybe modification with Iemitsu unable to speak freely about Kakishima due to conditioning, and what happened to the previous mayor...
- O.O.C. Is Serious Business: When Yamamoto drops from casual conversation to point-blank murder.
- The Omniscient Council of Vagueness: The Oyster Authorities, consisting of Hibari Main Family and Kokuyo Collective may be this.
- Papa Wolf: Reborn. And Iemitsu's actions. If you squint and close one eye and look reallly carefully? Averted by Timoteo with Xanxus.
- Persona Non Grata: What Iemitsu is experiencing. It may have to do with getting his boss to seal the flames of Tsuna. Kokuyo Guardian/ Daemon Spade's 'Golden Goose'.
- Rainbow Motif: Can't have a KHR fanfic without the Seven Flames of the Sky. More of a big deal in Kakishima than the norm. Must be the introduction of European weapons and later on, Vongola Primo and his Guardians.
- Screw This, I'm Outta Here: Iemitsu's really happy to be out of Kakishima. He wants to do this for Tsuna too, hence the flame sealing incident. Tsuna does not appreciate it, thank you very much.
- Slasher Smile: Hibari Vivien and Jeong-Seo Kaede. Also Reborn, judging from the pictures the author has created.
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Spiritual Successor: It is heavily implied that Daemon Spade possesses each Kokuyo Leader. - Story Arc: Still in the Oyster Daily Fortunes Arc after 14 chapters. Next Arc up is Blood in the Water.
- Super-Strength: Hibari may have reinforced his tonfa with them.
- Taking You with Me: What the Mafia thinks the agnelli di Dio happened. The truth is much more complicated.
- There Are No Therapists: Averted in this case. Not so with Xanxus and his father issues.
- Vitriolic Best Buds: What Tsuna and Mochida are.
