No Oni, Yattoko (CR 14)

Huge Outsider (Evil and Shadowlands)
Alignment: Always chaotic evil
Initiative: +5 (Dex); Senses: tremorsense, Listen +19, and Spot +19

AC: 20 (-2 size, +5 Dex, +7 natural), touch 13, flat-footed 15
Hit Dice: 14d8+70 (133 hp); DR: 15/jade
Fort +14, Ref +14, Will +14
Speed: 30 ft., burrow 20 ft.
Space: 15 ft./15 ft. (0 ft. with bite)
Base Attack +14; Grapple +18
Attack: 7 pincers +18 melee; or bite +18 melee
Full Attack: 7 pincers +18 melee; or bite +18 melee
Damage: Pincer 2d4+6; bite 2d6+9
Special Attacks/Actions: Improved grab, swallow whole, spell-like abilities, fear aura
Abilities: Str 22, Dex 21, Con 20, Int 14, Wis 15, Cha 17 (Ego: 10)
Special Qualities: oni qualities, regeneration 4
Feats: Cleave; Combat Expertise; Great Cleave; Improved Sunder; Power Attack
Skills: Bluff +20, Climb +23, Concentration +22, Diplomacy +7, Hide +14, Intimidate +5, Jump +23, Knowledge (Shadowlands) +19, Listen +19, Search +19, Sense Motive +19, and Spot +19
Advancement: 16-24 HD (Large); 25-32 HD (Huge); 33-45 HD (Gargantuan)
Climate/Terrain: Shadowlands
Organization: Solitary
Treasure/Possessions: Standard

Source: Oriental Adventures

Improved Grab (Ex): To use this ability, the oni must hit with a claw attack. If it gets a hold, it picks up the opponent and transfers it to the mouth as a partial action, then automatically deals bite damage and can attempt to swallow the foe.

Swallow Whole (Ex): A yattoko 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 1d8 points of acid damage per round from the oni's stomach. A swallowed creature can escape by prying the oni's jaws open. This requires a successful grapple check against the yattoko no oni. (If the oni is dead, it takes 10 on its grapple check, but allies of the swallowed creature can also attempt to pry the jaws open.)

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

Spell-Like Abilities: At will - cloud of Taint, deeper darkness, desecrate, summon swarm; 3/day - Tainted aura. These abilities are as the spells cast by a 14th-level maho-tsukai (save DC 20 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 20) 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 +2 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.