In the end of if all maybe Lea is much more than Shizuka, through her grief veiled view, had seen before.
The first few years everything was alright. Nagisa was leading a happy life, he was a teacher, he had friends, his family was coming back together. What could possibly go wrong?
Then came the nightmares, the treacherous thought. What if I did this, what if I did that? Could he have been saved? He starts spiraling into depression and no matter how much Akari tries, not even with Ritsu's almost infinite wealth of knowledge, she can't pull him out of the hole he buried himself in.
A couple drinks too many, a busy road, pain and then a chance to make it all right.