[Jaruromania]

There's a lot of holes with the "It's all in Keiichi's head" theory.

Spoiler:

1) So if the murder was all in Keiichi's head, then where was Keiichi at the time? At the festival? Then, what's in a hallucination? Was he able to act sane during the festival without remembering a single thing about it? If he imagined murdering Teppei, shouldn't his actions/speech during that time at least mildly coincide with what he actually did? (i.e. swung bat at nothing or a rock as opposed to Teppei). Also, why would he go to the festival in the first place? That goes against everything he was trying to do. He carefully planned out the murder and prepared for it extensively, meaning he fully intends to carry it out. It's possible he was hallucinating without going to the festival, but that defeats the purpose of "It's all in his head" in the first place.
2) What about Takano? Was everything she said imagined too? Everything that was there? Tomitake's bicycle, the body, everything? What about "was the body buried properly?" It's possible he misheard that, but Takano said far too many disturbing things for them all to be imagined.
3) If it was imagined, then where'd the bat go? If Keiichi took the bat out, it means that he seriously intended to kill Teppei, doesn't it?

I think that they were lying in order to protect him/Satoko.