Yuria Hinanawi (比那名居百合安) - Probably will be the best-ass final boss of the 1st generation of the SPM series

If you think Tenshi's attacks are the damn best ass in SWR due to the massive Master Spark spamming, then you have to think again since her younger sister in my Touhou headcanon, Yuria, is even more badass than that of her older sister.

The only human left in the Hinanawi clan after the whole family became Celestials, she thought she cannot gain a divine nature like the rest of the clan until she is revealed to be a very distant relative of a medieval saint by Megumi, and at that point, she automatically became officially recognized as a saint by the eye of God. But shortly after the attainment of sainthood, she is trapped in the Elysium in an accident (maybe involving her falling into a hole like the human children in Undertale), and remains trapped, even after it has been 12 years since she attained sainthood, and nobody in the Elysium ever care of bringing her back to the Surface (even though some of the residents of Elysium around her do notice of her presence there).

The backstory of this character also vaguely resembles Byakuren's, but the most amazing aspect of this character is not the backstory, but her battle mechanics: (WARNING: Spoiler alert!)

In-battle, you cannot harm her in any way, and any attempts to attack Yuria will result in a miss, making "killing" Yuria impossible.

In battle, she also alternates between different movement modes for the protagonist's Pneuma Cores, theirselves based on the Undertale SOUL Modes. The "Megumi Mode", which is just a pimped "Jump" SOUL Mode, will have the player to jump through swords, but there are also some swords that are of the Blue / Orange attack types, which requires the player to not move / move in order to not get damaged by them. Also some Megumi Mode attacks will switch into the normal mode after a certain amount of time (which the normal mode attacks still use swords as projectiles but in a different way) and vice versa. The "Yoshika Mode" (Basically just like the "Trap" SOUL Mode), will have the player's movement restricted to three lanes and they can only move up and down switching between the lanes as well as moving sideways along the lanes. In that mode, projectiles will come from either ends of the lane, and you will have to move and switch between lanes to dodge them. Yoshika Mode attacks will also have some that could switch back to normal and vice versa after a certain amount of time passed. And the "Ritsuko Mode", which is basically like the "Shooter" mode, must require the player to shoot at incoming objects to destroy them, (maybe) with some instances these objects spawn bullets as well. In this mode, objects move faster than normal, so it highly requires your reflexes to survive attacks in this mode. Unlike other Modes, Ritsuko Mode does not offer the function to switch between the normal mode and itself (as well as vice versa) after a certain amount of time passed (except for her final Spell Card (see below)).

Her Spell Cards (Magick Attacks) still use the normal movement mode, except for her final one, which she switches between all of the four available Modes in her battle during the duration of the Spell Card.

The best ass thing about her battle is the final Spell Card, which lasts as long as sh*t, and you have to face her projectiles in numerous ways during the Spell Card. And the other Pneuma Core Modes in the Spell Card do not switch from one of the three modes that represent each member of the Angelic Triad back to normal and then vice versa again, but they will switch between these Modes in an "erratic" way, which will switch between these modes without having each "Angel Mode" (which is what I dubbed the Pneuma Core Modes that are other than the normal mode which will be used in her battle) to revert back to normal between each mode, instead they will switch between all modes erratically, like if you expect Megumi Mode switching to Normal Mode after certain intervals (like in Sans' battle in UT), then it will not change to the Normal Mode, instead it will randomly (or at least pseudo-randomly) switch into another mode. I also planned of adding a visual gimmick that indicates which Mode does Yuria use during an attack by making her eye glow in the color that represent the Angelic Triad member that the Pneuma Core Mode represents (akin like Sans, but different).

Anyway, this perhaps will be the best-ass final boss battle in the 1st generation of games in the Sanctum Puella Mari series!