Giku

Recently Tracie wrote in:

I have a piece of calligraphy that I purchased 20 years ago at the monastery on Mt. Koya in Japan when I was an exchange student. At the time I just thought it was interesting but didn't look into its meaning.

Recently I was going through my things at my parents home and came across this piece of artwork again, I would like to know more about this character. The Japanese accompanying it says the pronunciation is Giku.

I can identify the character as gīḥ which fits with the Japanese pronunciation Giku, but I cannot find any more information about this syllable. I asked for help and my friend Maitiu replied:

In the East Asian tantric tradition at least the syllable gīḥ seems to be the bījā in mantras to the inner offering goddess Vajragītā [song of the thunderbolt]. I found Siddhaṃ mantras in two texts in the Taisho, T.867 and T.875.

T.867
金剛峯樓閣一切瑜伽瑜祇經
The Sūtra on all the Yogas and Yogins of the Vajra Peak Pavilion
唐南天竺國三藏沙門金剛智譯
Attributed to Vajrabodhi but it seems to be a compilation of ritual material rather than a translation of an Indian text.

一切如來內護摩金剛軌儀品第十
Chapter 10 – The Vajra Rite of the Internal Homa of All the Tathāgatas

[0266b18]
oṃ　va　jra　gī　te　a　gni
唵(引) 　嚩　日囉 (二合) 　儗 　帝　阿　儗 儞(二合)
huṃ　gīḥ
吽　儗(入聲)
[0266b18]

T.875
蓮華部心念誦儀軌
The Recitation Rite of the Heart of the Lotus Section

[0324b09] 內口供養。
The [four] Inner Offering [Goddesses]:
[0324b10] oṃ va jra lā sa haḥ 　oṃ va jra ma la traṭ
[0324b11] oṃ va jra gī te gīḥ 　oṃ va jra dṛ tye kṛ ṭ [this should be varjanṛtye kṛṭ]
[0324b09] 內口供養。

In the 16th section of the Sarvatathāgata-tattvasaṃgraha gīḥ occurs in a slightly different context but still connected with the word gītā.

STTS - ṣoḍaśamaḥ
Padmaguhyamudrāmaṇḍalavidhivistaraḥ

athāsāṁ mudrā bhavanti|
oṁ padmaratipūje hoḥ||
oṁ padmābhiṣekapūje raṭ||
oṁ padmagītapūje gīḥ||
oṁ padmanṛtyapūje kṛṭ||
oṁ dhūpapadmini huṁ||
oṁ padmapuṣpi hūṁ||
oṁ padmakulasundari dharmāloke pūjaya hūṁ||
oṁ padmagandhe hūṁ||