Hiro's actual sin lies inside the Time Skip.What we saw in the first chapter wasn't the worst of it; in the two years since that event, Hiro did something far worse — something like crossing the Moral Event Horizon, perhaps. Something that would make our Designated Hero much less sympathetic if we knew the truth. The Time Skip, therefore, is meant to hide this information until The Reveal in order to make it seem like less of a Shocking Swerve.
This is a sequel to Doubt and Hiro is the "Wolf" for this game.Not only does he get a rabbit mask, but in the cover page a person with a rabbit mask is next to him, wearing the same shirt the Wolves wore in Doubt.
The fat guy with glasses will play a key part later on.Why would a random character be introduced just to die on the exact same page? Why has no one come for the body? It seems to me that a fake-out is in order...Especially since in the mangaka's previous work a character we thought was dead in one of the first chapters turned out to be faking it and was the Mastermind behind the whole ordeal.
The guy with the lion's mask is Yuu all grown up.
The "Wolf" is the pig-masked guy.In the splash-page/page image, he's facing away from everyone else and is the one who is in the most shadows. And considering how the previous work had a clue on its splash page...
Kazu is the traitor.