Shigaraki Tomura is a villain and one of the main antagonists of the Ultimate Space & Jams Arc. His goal is to kill All Might "The Symbol of Peace," thus destroying the society he represents and to create a new one with a new form of justice in his own image. (Source: Wikipedia, My Hero Academia Wiki)

Calcifer is a fallen star who was caught by Howl. He didn't want to die, so he struck a deal with the wizard. Calcifer got Howl's heart and a prolonged life, and Howl received full access to all of Calcifer's considerable powers. As it turns out, neither of them liked it after a while, but it couldn't be broken by people who were part of the contract. When Sophie Hatter comes to Howl's moving castle, Calcifer recognizes that she is under a curse thanks to the Witch of Waste and that Sophie has considerable powers of her own of which she is unaware. To break his own curse, Calcifer offers to lift the curse placed on Sophie once she manages to break Calcifer's contract with Howl.