Seems odd that neither the solid reasons nor the emotional appeals worked, but exploding the golem and Arge seemingly risking great danger to save Exister (was it even necessary if Exister is so high-spec?) somehow made her realise the truth. Surely Arge saving her like that as if some subconscious act should reinforce the belief that Arge is Cyril even if without memories of it, like Exister has been claiming all along? It felt really contrived and anticlimactic to me, especially after this annoying and mostly pointless arc got dragged out for so long. Thank the gods it's finally over now, and the real manga can resume.