I very nearly took the easy way out on this one by picking a scene, any scene, from Grave of the Fireflies. Then I thought about the movie that JAFWA nearly made the horrible mistake of showing back to back with Grave of the Fireflies in a marathon screening one day: Windaria. [Aside: Fortunately the committee came to their senses and swapped a comedy in.]
My next possibility was the finale to Mobile Suit Gundam 0080: War in the Pocket which ends on a note of pure tragedy.
But as I thought on it I wanted to pick something where good came out of the sorrow, where the sadness is in the end a source of strength or growth for someone.
For such is the human condition: this too shall pass. What matters is that we learn from what passed, and build a better world from it. Or at least a better person.
This then led me to the Vision of Escaflowne, and to the passing of Nariya and Eriya, the Fortune Twins, in episode 21, Reaction of Fortune.
As cat girls Nariya and Eriya are victims of Fantastic Racism (warning: TV Tropes link) and are taken in by Folken who raises them from childhood in safety. Without putting too fine a point on it they then fall helplessly in love with their benefactor as they grow up (who is far too noble to take advantage of the ladies).
In time this leads to a sequence of events that can only be described as high tragedy, and for which the lead character Hitomi must bear partial responsibility.
Their deaths in Folken's arms are both heartbreaking and in my view the key to the resolution of the series.
Because Hitomi does accept responsibility for their deaths and at that point grows up (or starts to).
I've long thought that Escaflowne is a bildungsroman and the passing of the fortune twins is the key event that forces Hitomi to take responsibility for the consequences of using her powers.
More than any other it is the event that makes her decide to return to Earth (which is why I think the ending to Escaflowne is exactly what it needed to be).
Day 1 - Very first anime: Robotech, Gall Force, Vampire Princess Miyu
Day 2 - Favourite TV series: Card Captor Sakura
Day 3 - Your anime crush: Oh grow UP already.
Day 4 - Favourite Film: My Neighbour Totoro
Day 5 - Anime character you feel you are most like (or wish you were): Kinoshita (Rocket Girls)
Day 6 - Most annoying anime character: Lynn Minmei
Day 7 - Character you’d most like to slap: Hiyama Hikaru
Day 8 - Most epic scene ever: Launch day - Wings of Honneamise
Day 9 - Saddest anime scene: The passing of the Fortune Twins - Nariya and Eriya
Day 10 - Favorite slice of life anime
Day 11 - Favorite mech series
Day 12 - Best instalment of a franchise you don’t like
Day 13 - Worst instalment of a franchise you do like.
Day 14 - Current (or most recent) anime wallpaper
Day 15 - A reality check for a genre you like
Day 16 - An anime classic that simply doesn’t work for you.
Day 17 - Best Background Music
Day 18 - Best Five-team (?)
Day 19 - Change you’d like to make to any one anime
Day 20 - Most ambiguous anime character
Day 21 – Favourite OAV Series
Day 22 - Animation studio you'd most like to slap.
Day 23 - Anime you think had the best, or most intriguing art
Day 24 - Favorite anime hero or heroine
Day 25 - Best anime villain
Day 26 - Your favorite harem anime
Day 27 - Favorite anime opening theme song
Day 28 - Favorite anime companion/summoned creature
Day 29 - Best Anime Music Video
Day 30 - Favorite anime ending theme