Heidi (Haiji) is the main protagonist of the Hungry Joker manga series. He is a young scientist that was able to awaken the power of his mysterious black apple. To find out about his unknown past, Heidi joins the White Joker organization alongside his assistant Chitose Toriiooji. He is called Barschheit by Nacht, his older brother, and the only person that Heidi recalls from his past's memories.