Knew it was something like that, they wanted Sunao to look at what/who she is killing and not deny that she is destroying a life, which she kinda failed, but... nothing like confronting your own flaws head to head to discover your true strength.
Susuzumi has too much composure, really wanted to see him laughing at Madarai.
This chapter made me remember a detail about this manga that has me reevaluating if the Soul Shrine thing is really as random as I first thought... how Kazuya talked with his mother "shadow" in his dreams.
This mirage clearly is a ritual that demands certain preparations, but Kazuya's whole existence is very complex in nature, he does had/has a connection to his mother spirit, he inherited Kiriha in ritual when he was a newborn, Kiriha was still being used by his mother even then so when Kiriha came back to him the seal in his memory could have worked as a link/filter.
When I factor these things, how souls can connect to memory and conscience, the idea that expanding this inner space outward isn't exactly farfetched, in retrospect... I think we just needed a few more shows of barrier magic done so that it didn't feel so out of pocket, but after thinking about it a little I can accept it, and funny enough... the fact that it isn't a very used or understood technique helps a lot, it is like something they didn't need to explore as most of their powers come from using supernatural "tools".
But I still hope Kazuya isn't able to use Soul Shrine, as I said earlier his "kit" is already overloaded and overpowered, he already became able to use little practical barriers and he is the only person we know capable of keeping and even using multiple Tsugos at the same time, I would prefer if he focused on what he already has than seeing him get another ridiculously powerful ability... "simplicity" is good too.