A transcendent Reimu summon by a master of the Fourth Holy Grail. Her summoning into the war bought fourth what changes and will these changes be able change the final outcome of the war?

The Fourth Holy Grail War always ended in tragedy and along with many of its variations that exist in parallel with it. Tired of the eternal same ending of the war, an old observer finally decided it is time to create a new ending and variations for the war. To do so, the old observer invited another fellow observer to intervene in his behalf,...