SMT demons and Touhou dual-references. Backstory and character designs highly prominent for the latter!

": Rather obscure reference in Touhou. Dialogue, song title, spellcard, those non-game albums, manga example / allusions.
   Manga chapter topics are free game, though, even if they're not read nearly enough.
^: Rather obscure SMT use. Persona 2, DemiKids, not-followed-up SNES days, etc. Devil Survivor 1/2, Strange Journey, SMT 4, Persona 3/4

"Acala
"Agni
Alice
^"Ashinaga-tenaga
^Amanojaku
Bai Zhe (Hakutaku)
Bishamatoten
"Brahman
^"Bunbuku Chagama
Brockengenspenst
Chupacabra
^Dullahan
Doppelganger
"Durga
"Garuda
"Genbu
Gozu-Tennoh
Hecate
Hare of Inaba
"Hanuman
Hobgoblin
Huoniao
"Itsumade
"Izanagi
Jinwu (Huoniao)
^Kaguya-hime
"Mandrake
Mamedanuki
^MIB
Mishaguji-sama
Mermaid
Nekomata
Nue
^Owatatsumi (Wadatsumi, Ryujin)
Take-Minakata
"Tesso
^"Tsukuyomi
Otohime
P'eng (Dapeng)
Pixie
"Polaris
"Preta
Raiju
^Red Cloak (Aka Manto)
Sariel
"Salamander
^Shuten-doji
^"Skyfish
"Slyph
"Sokushinbutsu (Daisoujou)
"Tamamo-no-Mae
Tengu
Tsuchigumo
^Tsuchinoko
^Vampire
^Werewolf
Yama
^Yamawaro
Yuki-onna
Yatagarasu
^Zashiki-warashi
"^Zenki-Goki

I swear Prince Shotoku appeared somewhere in Persona 1/2, but I can't find him again.