there's a book 'Secrets of the Ninja' by Ashida Kim (Dojo Press) that has been floating around for a couple of years as a pdf online. It shows the positions & explains their relationships.
I tried out the hand positions a few times & they are deceptively difficult to get right. They produced the same kind of endorphin euphoria response that you get from a good yoga or ma workout in me.

Ashida Kim is a fraud and everything he prints are lies.

I compared Kim's material with Liang Shou-Yu's and whilst both do leave out certain (key) information, there are many similarities in the finger knitting methods and some glaring differences. There were also some "discrepancies" in Kim's manual, but without further research it is difficult to ascertain any sort of accuracy unequivocally. In any case, Kim's manual certainly uses the right "lingo".

This is one of the difficulties I face in my research, because the teaching is traditionally closely guarded, and those in the know, are unwilling to share the investment in time and effort, for various reasons - which are understandable.

The other difficulties I face, is that hand seals are only a small part of a larger body of related knowledge that also include body seals, mantra (sounds), breath, visualization, and meridian/channels (among other things). So, invariably my research at the moment tends to be broad rather than deep as I would like it.

Why not then focus your interest on 'kundalini'. Seems to me its the same force - different name. There appear to be many roads to the same destination & the yogic methods are much more available. I would think you would stumble across some of the information you are looking for there as it does seem there is a common 'root' teaching the rest evolved from in different regions incorporating the beliefs of the region into the art/path.
I suppose Im saying approaching from another direction may reveal some more of the info you are looking for.

PS Fellow Aussie here

No, this is right; everything Christopher Hunter (aka Ashida Kim) publishes is either lies or stolen from someone elses work.

If you want a description about kuji kiri / kuji in try contacting Tanemura Shouto or reading his book Ninpo Secrets, it has some information regarding this topic.

Eyrie, what key informations are missing in Shou-Yu Liang`s book? I have that book, and found the section on the seals very interesting. However, since I never read anything about it elsewhere, I can`t compare it with anything.

This has nothing to do with the discussion. Keep this nonsense out of this forum section.

I am an east asian studies major, currently working on my honors thesis in the area of Shugendo.

If anyone wants to understand how the mikkyo techniques of Buddhism developed into the kuji-in and then spread to ninjutsu, you must explore this religion.

In Japan the Shugenja/Yamabushi was a wandering mountain ascetic whose doctrine combined Shingon with shaman, daoist, and shinto techniques and beliefs for the purpose of accumulating occult power and eventually transforming into a Buddha in their current body. They developed the kuji-in, as well as being indirectly responsible for the development of Noh theater (which was derived from their meditational dance), and many other mountain practices. Also, the ideas of Honjisuijaku, allowed for the interweaving of Buddhist and Shinto cosmologies throughout Japanese religious thought, was developed and spread by these independent monks.

Their frequent use of magic to cure diseases, perform excorsisms, walk barefoot on burning coals and the edges of katana without harm, were all attributed to the power they achieved through mountian training, standing under waterfalls, fasting, canting, and performing the kuji-in.

The traditional ninjas took advantage of the commonly held belief in the kuji-in to strike fear into their enemies. Their have been attempts made by scholars to link certain ninja clans historically with groups of shugenja, but because of the gross lack of written documentation surrounding both traditions, it has been very difficult.

Hope this helps.

Could you provide bibliographic references, please?

Specifically, I'm looking for a correlation between such hand formations and internal energy cultivation.