The final episode of school days. Just about everyone that commented on that video said they felt depressed after seeing it.
I won't say who died, but after episode 6 it became obvious it was moving from the happy series it started as & someone was going to die, especially since the series was tagged horror (mainly for the last episode).
The creators would've went with one of the good endings, but that would be too simple (wish they didn't shove all the scenarios into the last episodes).
In the Eroge, 4 of the 21 endings had someone die, either Matoko, Sekai, Kotonoha, or both Sekai & Kotonoha.

Moonlire winry
I have to say Claymore Teresa's death tho I knew she was going to die, I kinda forgot & they gave me hope & I have to say It was the most shocking... I cried..
The whole Anime was bad like that sooo Violent!!!
Also Wolf's Rain... I didn't like any of the deaths in that one...

Wolfs Rain...I remember that series.