Kokoro is a heavy novel. The true story lies with Sensei, and his part is elaborated in the third part. This is a story about loneliness, trust, family loyalty, traditions, and so much more. The ending is depressing! Life is too for that matter, and the feelings and thoughts of Sensei are intensely realistic. For me it was difficult to like Sensei throughout the story. There are times when he is kind and compassionate, and other times when he is selfish and irrational.
I thought the progression feelings of Sensei towards Obachan - suspicion to adoration to jealousy - were written spot on. I suppose it must be cultural that Obachan didn't know about K's feelings towards her, and the competition that did lie between them. In today's world, I would call her a complete idiot, but then, as Sensei often describes, that was a time when no one was expressive with their feelings.