Statting Touhou

[Prime32]

Byakuren Hijiri (Hopeless Masquerade version)
NG Elan Monk 1/Unarmed swordsage 1/Psychic warrior 13/Jade phoenix mage 5
Feats: 1: Monastic Training (psychic warrior), 3: Psionic Weapon, 6: Dorje Blade^HC, 9: Dorje Mastery^CP, 12: Snap Kick^ToB, 15: Tashalatora^SoS, 18: Sun School^CW
Bonus Feats (PsyWar): 3: Psionic Meditation, 5: Craft Dorje, 7: Deep Impact, 10: Psychic Renewal^ToB, 13: Practiced Manifester (psychic warrior)
Bonus Feat (Monk): Stunning Fist
Maneuvers: Action Before Thought, Dancing Mongoose, Desert Tempest, Flashing Sun, Pouncing Charge, Shadow Noose, ?, ?, ?
Stances: Aura of Triumph, ?
Equipment: Bracers of lightning^MIC, Dorje of energy flash^CP, Dorje of energy stun, Monk's belt, Rings of force armor^MIC

Powers Known
1: Adrenaline Boost^CP, Burst, Mighty Spring^CP, Thicken Skin, Vigor
2: Animal Affinity, Body Purification, Detect Hostile Intent, Extend Reach^CP, Hustle, Power Weapon^CP
3: Dimension Slide, Evade Burst, Graft Weapon, Mental Barrier, Stygian Bane^CP
?

[Prime32]

Updated Koishi build.

Koishi Komeiji
NE Ex-Vecna-blooded^MM5 daelkyr half-blood^MoE Lurk^CP 13/Ebon saint^CP 5/Bloodhound^CAdv 2
Skills: Hide, Listen, Move Silently, Sense Motive, Sleight of Hand, Spot, Tumble
Abilities: Focus on Int, Dex and Con
Feats: 1: Keen Intellect^OA, 3: Willing Deformity^EE, 6: Deformity (madness)^EE, 9: Darkstalker^LoM, 12: Expanded Knowledge (synchronity^CP), 15: Practiced Manifester (lurk), 18: Endurance
Bonus Feats: Combat Reflexes (serpent armor), Combat Expertise (flaw), Improved Trip (flaw), Symbiont Mastery^MoE (racial), Track (mask of the tiger)
Flaws: Light Sensitivity^Dr328, Short Attention Span^Dr328
Powers: Catfall, Chameleon, Cloud mind, Danger sense, Death urge, Defensive precognition, Detect hostile intent, Distract, Mass cloud mind, Offensive precognition, Offensive prescience, Psionic contingency, Psionic freedom of movement, Psionic tongues, Temporal acceleration, Wall of ectoplasm, ?
Equipment: Boots of agile leaping/Boots of the battle charger^MIC, Collar of umbral metamorphosis^ToM, Hathran mask of true seeing^UE/Mask of the tiger^MIC, Hat of calm emotions, Ring of evasion, Serpent armor^MIC, Tentacle whip symbiont^ECS (racial)

With the combination of Vecna-blooded, Darkstalker, Deformity (madness), Ebon Saint and cloud mind... You are immune to mind-affecting and divination effects (and people trying to read your mind might be dazed due to daelkyr half-blood), you can hide from any sense even in plain sight, people who see you must make Will saves or ignore you, and you can make people forget they met you.

Bloodhound's Nonlethal Force ability synergises with Ebon Saint's Disappear from the Mind. You can also pull off some shenanigans with readied actions by combining synchronity with Bloodhound's ability to ready actions 10 minutes in advance.

Also you can use your tentacle whip to pull off lockdown tactics.

EDIT: The faint memory^MoE power offers an alternative way of avoiding notice.