Jewel case for Touhou Hisoutensoku
Full: August 15th, 2009 (Comiket 76)
Competitive Fighting Game
Single-player Story Mode, Human vs. Human Match, Human vs. Computer Match
Pentium 1GHz, 1.02GB on HDD, Direct3D, DirectX 9.0c (April 2007 update), 128MB VRAM, DirectSound, 1GB RAM
Touhou Hisoutensoku ~ Choudokyuu Ginyoru no Nazo o Oe (東方非想天則 ～ 超弩級ギニョルの謎を追え, lit. "Lacking the Perception of the Natural Laws of the East ~ Chase the Enigma of the Gargantuan Guignol") the 12.3 instalment of the Touhou Project, created by Team Shanghai Alice, with Twilight Frontier's collaboration. It's a standalone expansion pack to Scarlet Weather Rhapsody with five new characters and three story modes. Its events occur after those in Undefined Fantastic Object; it was developed and released alongside that game.
Touhou Hisoutensoku retains the same spell cards, spirit orbs, and weather present in Scarlet Weather Rhapsody, but also introduces new playable characters, spell cards, and weathers. Many existing spell cards, weathers and graphics from Scarlet Weather Rhapsody have been altered and in addition to the new characters, existing characters all have new spell cards. Additionally, each playable character now has a system card (e.g. healing, weather change, bombs, etc.) associated with her that's usable by any character once unlocked.
Touhou Hisoutensoku is the third fighting game in the Touhou Project and like its predecessors, Immaterial and Missing Power and Scarlet Weather Rhapsody, Touhou Hisoutensoku is a collaboration between ZUN and Twilight Frontier. Due to that collaboration, its art was drawn by Alphes and the music was composed by U2 Akiyama, both from Twilight Frontier.
"Hisoutensoku" is a reference to its predecessor Hisouten (Scarlet Weather Rhapsody), and is also the name of a giant doll within the game. It also refers to "Hisou-hihisou-ten" ("the sphere of neither perception nor non-perception"), which the title of its predecessor was also based off of.
Touhou Hisoutensoku introduces four new characters in the game. All four of them have previous appearances in earlier danmaku games. Hong Meiling reappears in a fighting game because she first appeared in Immaterial and Missing Power, but had no appearance in Scarlet Weather Rhapsody.
ZUN said in a radio interview that Wriggle Nightbug and Nitori Kawashiro were originally slated to appear in the game, but were scrapped due to time restraints. Kaguya Houraisan and Fujiwara no Mokou were also considered, but it was decided that they were too strong.  Instead, Twilight Frontier decided to put in mostly weak characters, as they would humorously face off against the very powerful characters featured in Immaterial and Missing Power (most every mainstream character was featured there). Sanae Kochiya was added instead of these possibilities, and perhaps made as weak as she is on purpose.
A mysterious giant is seen wandering around Gensokyo. It can suddenly appear and can just as suddenly vanish seemingly without a trace. Everyone who sees it becomes curious and wonders about the truth behind this strange sight. Sanae Kochiya, Cirno, and Hong Meiling each have their own fears and dreams about the giant, and each sets out in pursuit of this roaming behemoth.
Exploring the Forest of Magic, the Scarlet Devil Mansion, and other locations in Gensokyo, the heroines face many challenges and obstacles in their pursuit of a mystery that's far deeper than it first appears.
Touhou Hisoutensoku has 18 tracks, plus music imported from Scarlet Weather Rhapsody. Except for two tracks, all the music was composed by U2 Akiyama. Only the tracks Unknown X ~ Unfound Adventure (アンノウンＸ ～ Unfound Adventure) and X and the Floating Objects in the Sky (空に浮かぶ物体Ｘ), two last boss themes, were composed by ZUN himself.
All the character themes are arranges from the previous games. For the reintroduced characters a new theme was composed. For some characters, their theme in Touhou Hisoutensoku is a stage theme from their previous game. For instance, Hong Meiling and Patchouli Knowledge their theme in Touhou Hisoutensoku were both the stage 3 and stage 4 theme of Embodiment of Scarlet Devil respectively. Reimu's theme is from Seihou Project's Shuusou Gyoku and Alice's theme is from Mystic Square's Extra stage.
After the release of the game, the Touhou Hisoutensoku ORIGINAL SOUND TRACK (核熱造神ヒソウテンソク 東方非想天則 ORIGINAL SOUND TRACK) was released containing 21 tracks from Touhou Hisoutensoku and comments from ZUN and U2 Akiyama. Additionally, U2 Akiyama arranged Unknown X ~ Unfound Adventure for the CD.
A hidden track not seen in the Music Room of Touhou Hisoutensoku could be heard when you play as Reimu and are in the third round in a normal fight. When the spell card Fantasy Nature is unleashed, an arrange version of Eastern Mystical Love Consultation is heard in the style of Hokuto no Ken (Fist of the North Star). 
- The lack of an English subtitle has western fans also calling it Soku or simply 12.3.
- Due to a mistranslation, some western fans called it and still call it Unthinkable Natural Law or UNL for short.
- Touhou Hisoutensoku: Version 1.10a Update (Note: When you browse for your game folder during installation, it will add a "/th123" string to your selected folder address and change the installation location. To properly install, either type in your folder address manually, or delete the "\th123" string from the folder address after selecting your game folder. Not only this, but it is recommended to install somewhere where you have full write permissions in Windows 7.)
- Touhou Hisoutensoku: Official Site
- Touhou Hisoutensoku: English Patch (Requires v1.10a)
- Touhou Hisoutensoku: Weather Patch
- Scarlet Weather Rhapsody and Touhou Hisoutensoku Gameplay Wiki (Note: As of March 2011, in need of donations to survive.)
- Voice Mod (Note: Go to the Voice Mod article for description.)
- Beta Voice Mod v014
- v020 Patch for Beta Voice Mod
- Soku+ patch download page
- Nae Radio (September, 2009). "Interview on Nae Radio (September 2009)". http://en.touhouwiki.net/wiki/Interview_on_Nae_Radio_(September_2009). Retrieved August 29, 2011.
- "Video Example". http://www.youtube.com/watch?v=8hSWYyi5BjE. Retrieved August 29, 2011.