I will attempt to roughly summarize the story-relevant sections of the LAST VISUALIVE, as a guide for non-Japanese speakers seeing it tomorrow or on Sunday. OBVIOUS SPOILERS.
The show opens with a speech from Marrow, the winged character in black with braids. Marrow seems to be some kind of angel of death and also a representative of the moon eternally watching humanity's sins. Luckily his speech is in the tour pamphlet, so I can give you a full translation:
"Why do people repeat the same mistakes?
Even those who share the same blood,
even those who once loved each other,
fight amongst themselves,
and then regret the foolishness of the sins that they committed.
The countless arrows that rain down from the sky,
the corpses that lie, piled on top of each other,
the souls of the men who have been taken by death,
they call to us.
Now, another man goes to meet his death.
You foolish ones, so evanescent.
All we can do is welcome you."
There are images of soldiers charging into battle, then we skip ahead to the aftermath. Only Yoshitsune (GACKT) is still barely alive. Looking over the devastated battlefield are his half-brother Yoritomo (wearing gold) and Yoritomo's vassal Kagetoki (wearing black).
Yoshitsune and Yoritomo originally had a trusting relationship, but eventually Yoritomo began to suspect that Yoshitsune was plotting against him and decided to defeat him. In the MOON SAGA story, this is spurred on by the machinations of Kagetoki, and Yoritomo's wife Masako, who is afraid of Yoshitsune's demonic powers and wants to turn her husband against him. At the end of the MOON SAGA novel/second play, Masako even made a deal with the demonic entity En, allowing him to possess Yoritomo. Yoshitsune finds out about this and vows to release Yoritomo from his possession. Due to the time skip between the novel and this scene, it's unclear if Yoritomo is still possessed or not.
Yoritomo is clearly upset to see his younger brother dying, and hesitates as Kagetoki repeatedly requests his orders. Yoshitsune calls out "Brother" and then wills Yoritomo to finish him. Yoritomo finally comes to a decision. "Kill him."
The archers fire, leading into the first song, "Arrow".
During "Akatsukizukuyo -DAYBREAKERS-" we get to see some of the battle that was skipped in the opening video. There's no dialogue, but the characters depicted in the death scenes are Ise Saburo, Sato Tadanobu and Musashibou Benkei, Yoshitsune's three surviving vassals (the fourth, Tsugunobu, was killed during the plot of the second MOON SAGA play).
The next movie is a flashback to 9 years previously, when a 21 year old Yoshitsune arrived from Mutsu Province to assist his brothers in fighting the Heike clan. Yoritomo is the first to see Yoshitsune, and clearly terrified by his appearance, he races ahead to warn another charcter who isn't clearly named, but is also a brother of Yoshitsune (historically speaking, probably Noriyori). Noriyori is glad to meet his younger brother for the first time, grateful for his loyalty, and tells him he resembles his late father. However, his demeanor changes when he suddenly notices a supernatural prescence behind Yoshitsune- presumably that of Kage, the Mononoke (spirit) that follows Yoshitsune and is only visible under moonlight. He asks if the prescence is Yoshitsune's "follower", and Yoshitsune replies that he is "family". Cue Utakata no Yume.
After the song "Youranka-LULLING", which I suspect is from Noritsune's point of view, we see Noritsune's death scene from the second MOON SAGA play. Noritsune and Yoshitsune are in an alternate dimension created from the clash between En, who was possessing Noritsune, and the demon within Yoshitsune. Yoshitsune is trying to convince Noritsune to return to the world of the living, but Noritsune, who slaughtered most of his own clan while possessed, thinks it is too late and chooses death. In the play, he kisses Yoshitsune on the lips while saying his goodbyes. Yoshitsune is pulled back into reality. The video pauses to reveal that the Camui Gakuen students are watching it. The contents of the Gakuen section vary depending on the show, so I won't go into that here.
After the "fun" part of the show, we get back into the story. First there is a video with another speech from Marrow about human nature, showing the deaths of many characters from the MOON CHILD movie, to the Returner music video, to the DIABOLOS tour story. Marrow asks a series of questions, "Why do you repeat the same mistakes?" "Why do you fight even with those you once loved, and kill them?" "Why is it that you know your own evil and yet refuse to acknowledge it?" "Why do you try to become gods?", etc.
Then we see Yoshitsune drinking sake under the full moon. He is quickly joined by his friends, including some who shouldn't be present at the same time if this is a flashback (it isn't). They start talking about everything they went through together, and how they are glad for it. Some characters' expressions seem to indicate that they know they are all dead and Yoshitsune is dying, but he doesn't. They all repeat the Oath of the Peach Garden ending in "...though we cannot wish to be born on the same day, we wish to die so", after which Yoshitsune says that he is tired, and begins drifiting off to sleep. His friends crowd around him, making jokes and encouraging him to wake up.
He then awakens back in reality, after being filled with arrows by Yoritomo's army, whimpering in agony. He tells his friends that he'll be there to see them soon, then pulls himself together enough to say clearly, "It's a beautiful moon tonight. A really beautiful moon."
This is followed by Setsugekka, in which GACKT appears onstage as Yoshitsune full of arrows, while the deaths of all the characters from the MOON SAGA plays and earlier in the show play behind him. The curtain closes and the show ends with a message from GACKT, "The last moon at sunset shines on the flowers". He tells us that when we are stuck in life, to try taking a step forward, as the moon will light our way."