No Oni, Tsuburu (CR 16)

Huge Outsider (Evil and Shadowlands)
Alignment: Always chaotic evil
Initiative: -1 (Dex); Senses: Listen +18 and Spot +18

AC: 27 (-2 size, -1 Dex, +20 natural), touch 7, flat-footed 26
Hit Dice: 15d8+75 (142 hp); DR: 15/jade
Fort +14, Ref +8, Will +7
Speed: 10 ft.
Space: 15 ft./15 ft.
Base Attack +15; Grapple +19
Attack: Bite +22 melee, 2 claws +17 melee
Full Attack: Bite +22 melee, 2 claws +17 melee
Damage: Bite 2d6+9, claw 2d4+4
Special Attacks/Actions: Improved grab, swallow whole, feed, spell-like abilities, fear aura
Abilities: Str 28, Dex 8, Con 20, Int 11, Wis 7, Cha 10 (Ego: 7)
Special Qualities: SR 26, oni qualities, regeneration 5
Feats: Alertness; Awesome Blow; Cleave; Great Cleave; Improved Bull Rush; Power Attack
Skills: Bluff +18, Concentration +23, Diplomacy +4, Intimidate +20, Knowledge (Shadowlands) +18, Listen +18, Search +18, Sense Motive +16, and Spot +18
Advancement: 16-24 HD (Huge); 25-32 HD (Gargantuan); 33-45 HD (Colossal)
Climate/Terrain: Shadowlands
Organization: Solitary
Treasure/Possessions: Standard

Source: Oriental Adventures

Improved Grab (Ex): To use this ability, the oni must hit with its bite attack. If it gets a hold, it automatically deals bite damage and can attempt to swallow the foe.

A tsuburu no oni that hits with a claw attack grabs as above. If it gets a hold, it picks up the opponent and transfers it to the mouth as a partial action, automatically dealing bite damage as above.

Swallow Whole (Ex): A tsuburu no oni can try to swallow a grabbed opponent of Medium-size or smaller by making a successful grapple check. Once inside, the opponent takes 2d6+9 points of crushing damage per round plus 1d8 points of acid damage per round from the oni's gullet. A swallowed creature can cut its way our of the oni's gullet by using claws or a Small or Tiny slashing weapon to deal 50 points of damage to the stomach (AC 20). Once the creature exits, muscular action closes the hole; another swallowed opponent must cut its own way out.

The oni's interior can hold two Medium-size, four Small, eight Tiny, sixteen Diminutive, or thirty-two Fine opponents.

Feed (Su): When a swallowed opponent dies in the oni's belly, the oni feeds on the life force as well as the flesh. For every 8 HD or levels the oni consumes, it gains 1 HD. Feeding destroys the victim's body and prevents any form of raising or resurrection that requires part of the corpse. A wish, miracle, or true resurrection spell can restore a devoured victim to life.

Spell-Like Abilities: At will - cloud of Taint, deeper darkness, desecrate, doom, telekinesis, teleport without error (self plus 100 pounds of objects only - swallowed victims do nor count against this 100 pounds). These abilities are as the spells cast by a 15th-level mahotsukai (save DC 17 + spell level).

Fear Aura (Su): Oni are shrouded in a constant aura of terror and evil. Creatures within a 30-foot radius must succeed at a Will save (DC 17) or become shaken. Shaken creatures suffer a -2 morale penalty on attack rolls, weapon damage rolls, and saving throws.

Regeneration (Ex): Oni take normal damage from jade or Kuni crystal weapons, and from honorable or blessed weapons of at least +3 enhancement.

Immunities (Ex): Oni are immune to poison.

Resistances (Ex): Oni have cold, fire, and acid resistance 10.

Alternate Form (Su): Oni can assume any humanoid form of Small to Large size as a standard action. This ability is similar to the polymorph self spell but allows only humanoid forms. When using this ability, oni gain a +10 circumstance bonus on Disguise checks.

Telepathy (Su): Oni can communicate telepathically with any creature within 100 feet that has a language.

Skills: All oni receive a +10 circumstance bonus on Disguise checks when using their alternate form ability.

Evil Subtype

A subtype usually applied only to outsiders native to the evil-aligned Outer Planes. Evil outsiders are also called fiends. Most creatures that have this subtype also have evil alignments; however, if their alignments change, they still retain the subtype. Any effect that depends on alignment affects a creature with this subtype as if the creature has an evil alignment, no matter what its alignment actually is. The creature also suffers effects according to its actual alignment. A creature with the evil subtype overcomes damage reduction as if its natural weapons and any weapons it wields were evil-aligned (see Damage Reduction).

Shadowlands Subtype

Shadowlands are the source of evil in the campaign setting of Rokugan, the festering pit from which oni crawl, slither, and fly to wreck their foul destruction on humanity. The denizens of the Shadowlands are inhuman monstrosities. Many of them are spirits bound into corporeal form, and most are shapeshifters. Of all the creatures found in the Shadowlands, only the nezumi remain uncorrupted by the foul taint of the place - all others are utterly, irredeemably evil.

Shadowlands creatures share a certain immunities and vulnerabilities. They are immune to harmful effects of the Shadowlands Taint, for they are already fully corrupted by their very nature. Even if they have damage reduction, they are harmed by jade and obsidian weapons, and they cannot regenerate or naturally heal wounds dealt by such weapons. They are also affected by crystal weapons (Chapter 8, Oriental Adventures) (Note: Non-magical weapons made out of crystal, or crystal weapons created by means other than the Craft Crystal Weapon feat, have no special properties against Shadowlands creatures.)

For purposes of detect Taint, spellcasting, and other effects, a Shadowlands creature is considered to have a Taint score equal to half its Charisma score (round down). Undead creatures add +1 to this number, while outsiders add +2.