Tadano and Maki.
Heita appears in chapter 15 of the first season, after Kamimaru has told all the survivors to meet him at their cubes. He is in bed with his girlfriend, Ootsuki Maki, and says that they won't go and that they'll be together forever. They both die when they don't show up at the cube, along with all the others who don't go there. He was from cube 6, along with his girlfriend and Fuji Masaya.