Pass as I know neither.
Got to pass this round, I have no idea who they are.
Long story short:
Okabe is an inventor who claims to be a mad scientist and acts like he is paranoid to appear more interesting than he is. He accidentally discovers a way to send SMSs to the past and he can that way change the present. He end up being a target for the evil organisation called "SERN" that tinkers with time travel as well.
The Boy is a superhuman who has the ability to travel forward in time, giving him superhuman speed. After an accident, the boy ends up twenty years into the future where human kind has been destroyed. After fifty years alone, he figures out how to travel backward in time so he can try and save humanity, but accidentally regressed back to his youth in transit. Also, he became the greatest time-traveling assassin while trying to get back to his timeline.