Hiroshi is a character in the game, The Ao Oni. He is the main protagonist of the game, in addition to being the only character to survive and make it out of the mansion.
Bros watching PewDiePie's Let's Play of the Game wonder if Hiroshi became an Ao Oni too. Since when PewDie saw an Ao Oni "raping" one of Hiroshi's Friends & after their game of tag, he saw the raped girl & become an Oni. The game tells that he really bacame an Oni but it after he encounters the monster it is automatically a GAME OVER.
In his Let's Play of the game, PewDie names the main character HiroshiPEN (he meant to have named him Penis), and gives him the voice and personality of Consuela, a character from the TV-show Family Guy.