ShiShi SonSon is a special technique to cut through very hard materials. It's not clear how high its actual attack potency is:
- Kaku deflected it with Rankyaku Roudan
- Ryuuma was able to counter Rashomon
In contrast, Nigori-Zake overpowered Kaku's Bigan (a considerably more formidable technique).
Here's what would have happened: