Kurono Kei is the main character of Gantz. He's a high school sophomore who gets pulled into the Gantz game after he and Kato try to help a homeless man on the subway tracks—and both get hit by a train in the process. It's a pretty brutal introduction to the whole mess.
At first, Gantz constantly calls him degrading names like "Bitch" and "Loser," which fits the overall tone of how it treats its players. Eventually it just starts calling him by his actual name as things go on, though the damage to his ego was probably already done.
Content compiled by AnimeList.moe from publicly available sources.
