Like I commented on another site: This is so beautiful and I'm already crying. Indeed, I'm always emotional with this manga. Their bond is so deep, I can't see them having this kind of attachment with someone else... It's unique. I love them.
And it still hurts me to remeber Satoko saying she tried love, but it isn't for her. She is fragile and strong at the same time, I understand her... Now, she just wants to protect this precious Mashuu. I would prefer them to end up together, they are so wonderful, but I understand why the author won't finish this way: this isn't the conventional age gap romance, this is almost poetry.