As the series nears its end, we finally learn the whole truth about Chii's origins and who the twin who speaks to her in her mind really is. The story is quite tragic, and it helps us better understand why finding someone "right" is such a sensitive topic for Chii. Now, there's something that's been bothering me this whole time. They want to convince me that Hideki loves Chii, but up until this episode, he doesn't seem entirely sure. He cares for her, he likes how she worries about him, and he's lustful towards her... just like he was with Professor Shimizu or Yumi. So why does it have to be love with her and not just affection, like with anyone else he lived with every day? But that's just my interpretation. If the anime tells me this is a love story, I believe them.