This is just a flashforward to Fate/Extra with her guiding Hakuno fighting against seven competitors in obtaining Holy Grail. But also can't help but think this is what inspire the (really good) Last Encore OP. With her in her red dress fighting theatrical-like against shadow enemies.
But also could be flashforward to Lilim Harlor arcade collab with her fighting against her own seven Bestia.
4.
5.
Nero has been helping Hakuno all this time and then its Hakuno's turn helping Nero by relieving her of her past. And then they bump fist as if they're equal partner.
6.
Parallel when they both care to each other until the end (though Nero in Extra manga scene I posted can still respond and talk but they are still doomed to bad end as Hakuno has no way of saving her yet at this moment).
Basically they care toward each other until the end and its beautiful.