Alright, so a lot of people have been saying that the person who is killing off the new heroes is Takeizo Kensei, me among them. I wanted to summarize in this post everything that proves this and stuff.
This also includes what I think will be the major story arc of Season 2.
So, I'll start from the beggining of the timeline (note that "The Line" was the name of the most recent episode, which I believe is talking about the timeline, and how all the pieces that we were given in this episode from the past, present, AND future go together).
Kensei is a drunk. Quite famous and yet a drunk and not the best of all people. He is the head of his own 'House', for which his symbol (as we see when he carries his flag and on his sword) is the "Godsend" symbol.
Hiro enteres the past, and meets Kensei. Because he altered the timeline by coming back (or at least he thinks he did, and I think he was right), he stayed to fix it. He got Kensei back in order so the princess would love him. Meanwhile, Hiro himself falls in love with the princess. They go and do all the stuff, Kensei discovers his powers, and Hiro tells him about his own, and eventually it comes time to rescue the princesse's father.
They rescue the father, blah blah blah, and then Hiro teleports the princess out of danger in the midst of battle, to her suprise. She realizes that at the beggining it had been Hiro in Kensei's armor and that she loves Hiro, and they kiss. Kensei sees, and is wounded deeper than any mortal's cut could. He becomes twisted and evil.
Kensei and Hiro battle it out, as depicted by the painting, and Hiro escapes. Kensei vows to have revenge. Zoom up to around present time. Kensei is likely in hiding or something in his house in montreal (remember it had the "Godsend" symbol above it, which was Kensei's symbol), when the Boogeyman finds him and comes to him with a deal. Not sure exactly what this consist of, but the jist of it is that Kensei gets his revenge and the Boogeyman gets his revenge or just does all the evil he wants (not sure which - depends if there is a motive or not).
The boogeyman tells Kensei of Hiro's dad's location (since the Boogeyman had been in that group). The picture is marked by Kensei with his symbol and is sent to him. Hiro's dad knows what this means because he knows about Kensei and knows he can do nothing to stop it except wait and try to put up at least a bit of fight maybe.
Kensei kills Kaito Nakamura.
The Boogeyman, in the meantime, for whatever reason wants Angela dead or hurt badly. He sends her the same sign, and the Boogeyman uses his powers to make her see her worst fear - herself, because of all the bad things she's done - and she attacks herself in the nightmare.
I'm going to stop there and just list a bunch of proofs of why the killer is Kensei (and probably Adam Munroe), and then I'll give some proofs as to why Kensei might be Peter's dad.
WHY IS THE KILLER KENSEI?
- The killer sent pictures to the older heroes with the "Godsend" symbol on it, which is Kensei's symbol.
- This is why he would want to kill Kaito Nakamura - to get revenge on Hiro (This doesn't mean that he doesn't want to kill Hiro still, it was just one step in his revenge).
- The killer jumped off the roof with Kaito and survived, indicating regeneration
- It isn't so farfetched to think that regeneration means you can't die of old age (or even age at all). If he can heal all the organs and cells and stuff in his body, there's no reason to think he CAN die of old age. And we know that his cells and stuff do heal (or just regenerate, which still works) because otherwise how can a hole close up or a toe grow back?
- It explains why the Hiro/Kensei plot was given so much importance
...I think there were some more proofs that I thought of before, but I can't think of now.
WHY IS KENSEI PETER'S DAD?
- Angela said that Peter's dad was depressed (like Kensei), and tried to kill himself multiple times (since Kensei knows he can't die he was doing things that involved 'killing himself'). When Kensei revealed himself as who he really was and became evil, Angela claimed he had succesfully comitted suicide and that he was dead.
- This explains why Angela was one of the victims just like Kaito.
- This would make Kensei Claire's grandad which would make sense since Claire also has regeneration.
- This is how Kensei knew Peter and left a message for him in his house.
- Although I'm not convinced, this COULD be why the Haitin erased Peter's memory: because Kensei met with Peter, and Bennet and the Haitin didn't want Peter to get involved with Kensei's evil plots.
Anyways, that's it folks!

