This is a purely Muso Shinden Ryu point, I can only claim specificity to Ishido Sensei's line as well and this is my personal translation of an excerpt from his Muso Shinden Ryu manual, Ichimaki Omori Ryu Shoden. All mistakes are my own. With all that said, it's a surprise that this blog has any credibility at all...
I should point out that this article is almost completely useless without seeing the photos or, better still, having Ishido Sensei demonstrate this in front of you.
Gyakuto - Point 5
The Three Levels of Noto, established as if relating to "Shin*-Gyou-Sou" levels of ShodoThe first type, after completing the finishing stab completely, while keeping your eyes on the enemy, steadily bring the sword with both hands above the knee; from there, grip the koiguchi with the left hand and perform noto.
The second type, keeping the sword aligned to the front right diagonal, take your left hand towards the koiguchi to grip it and perform noto. This is so to perform noto with the left hand only.
The third type, while bringing the sword to the koiguchi, gradually shorten the distance of the left hand where it is supporting the back of the sword and then from there perform noto. This is comparable to the "Sou" (cursive script) type of character in Shodo.
The decision of which type of noto to use can depend on your feeling on that day or depending on the way that you start and end the technique.
* The three levels in Shodo are often referred to as "Kaisho" (printed text), "Gyousho" (semi-cursive text) and "Sousho" (cursive script). In this particular case, "Shinsho" is merely another word meaning "Kaisho" (printed text). For more information on Shodo I recommend visiting Yukiko Ayres Sensei's website https://yukikoayres.com/
Shodo images above courtesy of https://www.takase.com/library/glossary-japanese-calligraphy-terms/