Talk:Main Quest: Shimosa/@comment-173.32.36.73-20171020033845/@comment-4802891-20171020050252

Amakusa from alternate dimension was summoned in Shimosa as an Avenger after his death in the Shimabara Rebellion, worked with Caster Limbo (the handsome freak) to create the singularity and Swordmasters (from my understanding : corpses of either Heroic Spirits, Demons or just humans reanimated and buffed by the weight of their own karma) and turned the region in a world of filth, more fitting in his eyes (his grudge is huge, you see).

He had planned on using Kiyohime as a sacrifice but they all arrive in time to fight him. After a fierce battle he summoned his Reality Marble, a mental image of the hellpit Shimabara turned into at the end of the rebellion, and trapped them there to die. Thankfully, Muramasa understood the reason why he was summoned here : his power is to cute someone's karma, their past deeds that lead them to be who they are. And he did just that to Shirou, tracing a god-tier sword to cut down Amakusa, his Reality Marble and the corrupted castle in one swing. However, such a weapon depleted his lifeforce and he disappeared soon after.

The castle now in fire, they all fled except Musashi and MC because the former spotted her fated encounter in the flames : Sasaki Kojirou. They begin to battle, one showing his Infinite Sword (the skill to cut all possibilities at once) and the other trying to achieve her Zero Sword (the skill to eliminate all possibilities and focus on one single path). Both at an extreme, their duel should have no end but because someone witnessed the event, Schroedinger's cat style, a victor was decided, giving the upper end to Musashi (there's philosophy and poetry in all of this, but that's beyond my comprehension --or desire to). Musashi died from her wounds a smile on her face, saving MC by throwing him/her out of the window as Kotarou catches them.

After that, everyone go back to their home, happy ending! ---Caster is shown expressing his frustration at the failure of his scheme, but knows it has planted the seeds for something bigger that would benefit his unknown master.

Back at Chaldea, MC stumbled upon a video message Musashi recorded back when they met Dantes in the village : a warming "thank you and see you later, we will eat udon together" message as a closure to the chapter.