Guilty

'Guilty is Ikki's Master on Death Queen Island. His identity is unknown because he always wears a mask. He teaches Ikki to draw power from hate and to provoke Ikki into hate. He killed Esmeralda and just before he died, he revealed to Ikki that Mitsumasa Kido fathered 100 orphan children (only in the manga) and Ikki is one of them to provoke Ikki on a mission of hate and kill all that's related to Mitsumasa Kido.