If not for the tag I would have thought it was Mystia.

This is what Takanasi fears she will become to help him

She's already well on her way to be evil for his sake though (re: manipulating all her elder sisters, and thinking of doing the same to Inami)... Her misunderstanding of her brother's 'M' status is just slowing down the inevitable.

Myssa_Rei said:
She's already well on her way to be evil for his sake though (re: manipulating all her elder sisters, and thinking of doing the same to Inami)... Her misunderstanding of her brother's 'M' status is just slowing down the inevitable.

I fear what she might arrange to help her dear brother achieve the ultimate beating. I hope for a continuation or season 2 to find out