I'm starting to see a resemblance of how Samyu is acting here to how Reni was acting in her previous life as Rina. Given there was a friend/classmate/cousin(?) named Shiori that arrived to visit Rina who looked like Samyu but acted calm and collected like Reni, I wonder if the truth is that Rina wanted to be like her friend. This assumes that Rina never actually died and is actually in some sort of fugue state and is dreaming/hallucinating all this (not sure how I feel about that, btw). Reni would then be Rina's ideal self based on the personality of Shiori whom Rina looks up to. As for why Samyu, who looks like Shiori, might be acting like Rina it could be that Samyu is the real Rina and Reni is an imagined ideal self that Samyu has imagined into being. Or something along those lines.
Honestly, I dislike "it was all a dream" stories. I'd rather it all be real. However, a small part of me would like to see Rina find some way to grow strong enough to handle her "real world" with the help of Shiori who seems to care about her. Or maybe with the help of Reni. Like, say Reni makes a wish with all 7 jewels for Rina to be happy, giving strength to her past self in a sort of positive feedback loop. Then, Rina could live a happier life, slowly becoming her own version of her "ideal self" rather than just mimicking Shiori, eventually die of old age or what have you, and then reincarnate as Reni. Thus closing the circuit and explaining why Reni has such a strong personality when Rina originally lacked said strength.
Regardless, I heavily dislike the possibility that Reni's life was all fake and everyone she met were never real. Or worse, WERE real but ceased to exist after Rina "woke up" like with the Wind Fish.
