VARIABILE X is the 134th chapter of Akira Amano's Katekyo Hitman Reborn!
Synopsis
Xanxus coughs up blood, signifying that the Sky Ring had rejected him. Xanxus bitterly revealed that he and Vongola Ninth had no blood relation whatsoever, shocking everyone. Squalo tells Xanxus that he can understand him, angering Xanxus, who screeches that Squalo doesn't understand him at all. Squalo proves it by explaining that Xanxus was born in the squatters, but was gifted with the Flame of Wrath since birth, making his mother obsessed with the delusion that she had an affair with the Vongola Ninth and had Xanxus as a result. She brought Xanxus to Vongola Ninth, proclaiming that he was their son. The Ninth, who didn't recognize Xanxus at all, still adopted him as his official child.
As time passed, Xanxus's arrogance grew, knocking out people and destroying his surroundings when he didn't want to do something so trivial as eating with other branch families' boss candidates. Xanxus grew to adulthood without knowing the truth. However, soon, he found out that he was adopted, and that without Vongola blood, he wouldn't be accepted as the Vongola successor, causing him to stage a coup, resulting in him being sealed off with Zero Point Breakthrough: First Edition by Vongola Ninth.
Tsuna tells Xanxus that the Ninth didn't care about blood or anything, and that he loved him like a son. Xanxus, however, screeched that he didn't care, and that he only wanted people to praise him. He then orders the Varia to eliminate everyone. Belphegor reveals that the entire Varia would come soon. The Cervello disqualify Varia and attempt to let the watchers out, but the Varia sabotaged it, trapping them inside. Three Varia members arrive, but report that a person was taking them out, and that he was a demon. However, they were immediately incapacitated by a giant iron ball afterwards.
Characters
*Note: Bold + Italicized = First Appearance