After I got punched in the gut by Yuki Yuni is a Hero, I wrote a review

OK, here's your bleak ending:

Togo loses her sight, she visits Yuuna to only find out that her spirit has been sacrificed. The Ibotsuki visit Karen, Yuuna, Tougo and Sonoko only to find out more clearly about how they are unable to fight anymore and they are next. Causing even more drama, Fu determined to protect her sister, and Itsuki also going with her since her dream is no longer possible, but wants at least to support her and have faith in the world they live. They are overwhelmed, used Mankai out of desperation only to fail and to be teleported back to be logs like the rest... all worshipped by the Taisha and brought upfront again for the final battle where the curtain falls and the Vertex slowly consume the world. With our crippled heroes no longer able to fight, knowing that they won't escape this cycle of sacrifice, they stare blankly in the destruction rejecting this life of bleakness sapped from Yuuna's pervasive optimism, sapped from their dreams from losing their basic senses and abilities, sapped from any motivation, rejecting their hopeless fate by letting the world die so they can end this endless struggle removing any meaning from their lives.

Happy now?!
No?

Fine, here's something more in line with the show:

Everyone recovers but Yuuna, Tougo goes back down the nihilistic path that there is no hope only for the other girls that what Yuuna said was true: their memories are still intact, and despite her spirit no longer with them, she accepts the fact that she is gone, but at the same time takes on her ideal, but with more remorse, responsibility and maturity. It's not about whether one "lives" or not, it's about persevering with what is dear to you no matter what, that's what Yuuna would've wanted, which Sonoko also reinforces, despite being reduced to a log, she accepted her existence despite that.

/r/anime Thread