This is really sad how great of a character she is to die.
It's even sadder after watching Railgun T EP20
I feel like the studio published this on purpose to play with our feelings.
Yup. Cutting open a fully healed wound just to rub salt in it. Every scene of those 2 episodes had me thinking "none of this matters, you're dead!"
Worst of all is that Ruiko will probably never even know that she died, which is both a kindness and a cruelty but it furthers the meaningless of it all.
Now, if this had aired a good season-and-a-half earlier then we'd be saying something very different i'm sure.