If the boy dies, she goes full Light Yagami, as she connected with him and promised not to kill. Though since she's being pushed right now she might do so to defend him. This is just becoming a huge mess.
Nah
The soy boy has become her weakness.
She's become more careless by being around him.
And it all started because of him getting bullied.
She made the wrong decision when she decided to help, she made another mistake when she took a knife for helping him again.
Then let him get involved with him which lead to the Yakuza's brother dragging them both together.
I think all of you guys if not most of you agree that he's a poorly written morality pet for our protagonist and the way he keeps getting in the way puts him more in an antagonistic albeit unintended by him which denies us from having fun.
Btw at this pace I doubt this series will last long, author didn't think this through if the best idea he could come up was making this bullied kid become the sidekick of the protagonist.