Stage 1 boss.
Spellcards based on water, tridents and shark teeth.

Now we need an underwater themed Touhou game... (even if it could be hard since... aside of the amabie and wakisagi and nitori, i don't knw if there's more underwater youkai, and a seetting could be hard since A) Gensokyo doesn't have a sea/ocean, and B) it could be hard to do an underwater city that isn't already Atlantis, but then again, i'm sure Zun could try to do a setting based on it, i mean, there's the Beast Kingdom in Hell, and a space noah's ark in the cd dramas, soo i'm sure that an underwater city (or temple, or anything, maybe even a submarine) couldn't be that hard to do, right?)