I am currently running an Oriental Adventures (OA) campaign called The Divine Heir and the Jade Regent loosely based around the Pathfinder Adventure Path the Jade Regent with strong influences from Sekiro.  The first adventure is called The Ashina Legacy and is essentially the The Brinewall Legacy set in and completely converted to an OA setting.

I had to rewrite the adventure intro and re-theme the monsters but it worked well.  Here is the flowchart of the adventure (and campaign).

This one is lifted directly from the adventure and converted. My PCs never encountered them though as they were very cautious about exploring the castle more than they needed to.

Large beast, unaligned

Armor Class 15 (natural armor)
Hit Points 52 (7d10 + 14)
Speed 20 ft., fly 20 ft., swim 40 ft.
STR                 DEX                CON                INT                 WIS                CHA
17 (+3)        11 (+0)        15 (+2)        1 (-5)           13 (+1)        6 (-2)
Senses darkvision 60 ft., tremorsense 60 ft., passive Perception 11
Challenge 3 (700 XP)

Digestive Enzymes. A belostomatid injects a corrosive enzyme into its prey that both paralyzes and liquefies flesh. A creature that takes acid damage from a belostomatid’s attacks must succeed at a DC 15 Constitution saving throw or be paralyzed for 1 minute. For every round the creature is paralyzed it takes 1d2 points of Constitution damage (Note: This is used to track how close the PC is to death, it does not have any other mechanical effects).

Hold Breath. The dolphin can hold its breath for 20 minutes.

Stench. Any creature other than a belostomatid that starts its turn within 5 feet of a belostomatid must succeed on a DC 12 Constitution saving throw or be poisoned until the start of the creature’s next turn. On a successful saving throw, the creature is immune to the stench of all belostomatid for 1 hour.

Piercing Bite. Melee Weapon Attack: +5 to hit, reach 5 ft., one target.
Hit: 10 (2d6 + 3) slashing damage plus 3 (1d6) acid damage. If the target is a Large or smaller creature, it is grappled(escape DC 13). Until this grapple ends, the belostomatid can bite only the grappled creature and has advantage on attack rolls to do so.

Acid Spray (Recharge 6). The belostomatid spits acid in a line that is 30 feet long and 5 feet wide, provided that it has no creature grappled. Each creature in that line must make a DC 13 Dexterity saving throw, taking 10 (3d6) acid damage on a failed save, or half as much damage on a successful one.