Mana played with the fountain water and signed
In the original story of Swan, it started from the beginning with Sawa being abused left and right. Her only sanctuary was her fiancée Takashi, her best friend Mako, and her little brother Kai. Until all three were taken from her leaving her alone.
Eventually, when she got herself together, Sawa started bit by bit for the past three years pulling her objects of hatred apart.
She started out with making her father lose his position as a judge. She played with the minds of her attorney and the policeman. She made sure Takashi saw bit by bit who his wife really is, with him failing to believe her at every turn.
And then she went and destroyed Chiho's credibility slowly driving her crazy. Before taking her down completely.
Slow revenge is good isn't it, it felt so unbelievably good taking apart her enemies. Driving them insane and pushing them to the breaking point. That type of revenge must have soothed her soul.
But Mana wasn't like that.
She didn't think Sawa was in the right for playing with her enemies slowly especially when she has a child to protect. Many times, did she make mistakes going through her revenge scheme that could have downright pulled her son with her two.
Chiho original found out about Haru. It's easy enough to guess what she would do, kill the boy. But, ultimately Shunji would have died protecting Haru.
Sawa fully knows well how dangerous Chiho was, despite having evidence to completely take the women down she held of in favor of torturing her slowly, which led to Shunji's and her baby brother Kai's death ultimate death.
That's right Sawa would have been too late to save her little brother in the original story because she acted to slow in taking her down.
Mana knows how Sawa feels, but the experience she learned from another world about revenge told her this. For a woman like Chiho who could be highly unpredictable taking her down in one fell swoop before she harms more people is better.
Because True Revenge is that in, she'll have nothing to look forward to but happiness, with her family, with her husband, and with her child.
But that was Just in Mana's opinion.