Yeah, I've never seen sankaku like this. It looks aces. As you know, sankaku is usually from the front , which I hate doing. It always feels like I'm going to roll an ankle doing it. Plus it results in a tangle of limbs that make it difficult to transition out of. To be fair, my irrational dislike of it may be blinding me some here I can and do use sankaku from guard a fair bit (or did....might have to give it away now due to knee). I think this sort of entry would work well (pedagogically) with the Bischof roll series, as both of them are reliant on swinging a shin under yourself, momentum transfer etc. Seeing I taught them the Bischof, they should hopefully pick this up faster.