A Short, Miserable Life for a Short-Tempered Brother-Con [Crossover]

Sawada Anji isn't a native of this world. As the older sister of a certain good-for-nothing Tsuna, she knows that before her little brother becomes the Tenth, he'll spend years being bullied as a good-for-nothing. "Did I just hear someone call our Tsuna a good-for-nothing?" "Who bullied Tsuna? Step forward." "What did you say about my little brother? Are you asking to die?" Sawada Anji's temper raged for a long time, until a System bound itself to her. It said that in the future, many people would enter her world through dimensional rifts. As the only non-native in the entire world, she had to collect them into the System to keep them from disrupting the world as it was. And how was she supposed to collect these intruders into the System? Um... How about touching foreheads? Sawada Anji sneered. "Hah. It's just touching foreheads." From then on, she decided to learn the headbutting skills of a certain charcoal-haired boy, crashing into walls with all her might. The first time the System went beep beep beep, Sawada Anji followed its directions to an alley, where she found someone lying in a pool of blood and... a bloodstained long sword. The blue-haired boss, who had somehow gone from the Muken Prison to the living world, looked back with a gentle smile. Sawada Anji instinctively took a step back. Damn, the blue-haired boss right off the bat? She didn't think she could handle this. Was her head... hard enough? Later, Good-for-nothing Tsuna would often stare in horror as his sister, who'd been short-tempered for seventeen years, waited on her many "friends" with a sycophantic smile, bringing them tea and snacks. Original world: Vongola + Port Mafia + magical tennis Dimensional rifts involve: pirates, Hollow hunters, demon slayers, a certain hunter, ninjas, and more Reader's guide: - Goofy style - The characters belong to their original creators. Any OOC is on me. - Pairing undecided, but there will definitely be a pairing, and possibly unrequited love - The heroine is a short-tempered girl who's obsessed with her little brother Theme: Take chuunibyou all the way