Considering the various Call Backs across the Drakengard and Nier series (yes, including SINoALICE) are going to be prevalent not just in the story, but in the Weapon Stories and costumes. SPOILERS WILL BE OFF. YOU HAVE BEEN WARNED.
Drakengard 3
- Fio's "Intoner Girl" costume is based on One, with her costume story being from the perspective of the five Intoners.
- Akeha's "Intoner Assassin" costume is based on Two.
Nier
- Beastbain, Beastscourge and Beastlord are carry-overs from Replicant and Gestalt.
- The "A Fleeting (X)" Memoirs, dated from 2003, 2009 and then 2012, are from someone suffering White Chlorination Syndrome, which came from the result of Caim and Angelus's battle against the Queen Beast in Tokyo.
- The Iron Pipe Weapon Story is from the perspective of the Shadowlord. Fitting since he's Nier's Gestalt.
- Argo's "Patriotic Traveler" costume is based on "Father" Nier.
- In an alternate timeline, Hina Akagi and Yuzuki Kurezome join the Hamelin Organization, a group that plays a significant part in the game's backstory. Yuzuki ends up succumbing to the White Chlorination Syndrome and becomes a Red Eye.
NieR: Automata
- Akeha's "Mechanical Assassin" costume is based on the Commander.
- Fio's "Mechanical Girl" costume is based on 2B.
- Rion's "Mechanical Exile" costume is based on 9S.
- Akeha's EX Story involves her cutting a mackerel. Ending K involved 2B dying from eating a mackerel because the fish oil clogged up their systems, but not before making note of how delicious it was.
- Cruel Oath's Weapon Story censors two spaces, but those letters are N2, aka the Red Girl who are responsible for everything that's gone wrong throughout the game.
- The YoRHa-issue Blade Weapon Story in Automata was about a DJ, 24D who goes into Go Mad from the Isolation.
- The "Ray of Thought" Memoir has a Pod opening up, though it doesn't reveal which one it is.
- The song sung by Marie in her chapter is "Normandy" from the YoRHa stage play.
SINoALICE
- Saryu's Fabled Witch costume is based on Alice's Cleric class, Akeha's Fabled Assassin costume is based on Snow White's Breaker class (and given how her voice actress voices Snow's Foil Cinderella is one hell of an irony) and Noel's Fabled Weapon costume is based on Red Riding Hood's Paladin class.
- A section of Library with disembodied giant versions of Parrah and Noya appear in Chapter 3 of ''The Story of the People and the World", with a diary entry revealing that they ended up in this state due to a certain something entering it. And now they lie in wait for the perfect opportunity to restart "service", aka the SINoALICE Project hinted at in the Acts of Authors and SINoALICE...
Drakengard
- The Final Boss of Chapter 4 of The Story of the People and the World, just like Drakengard and Final Fantasy XIV's Dark Apocalypse raids before it, is a Grotesquerie Queen, causing a Mass "Oh, Crap!" and collective Heroic BSoD among players of those two games. And like Drakengard, the boss fight is a rhythm game.
- 10H's Abstract Savior costume story ends with the opposite of the Watchers' commandments:Speak of me. Paint my likeness.
Write about me. Carve me into stone.
Sing of me. Call for me.
Please. Please realize...that I am here.
