Well...
The doll is a transmitter device, it can teleport, and has a microphone. On the other hand...
Peridot will be cursed to die repeatedly by Arwin.
I guess Latte really have her own magical power but that part is unclear to me.
Bishot and Esula seems going to be a couple. (I guessed that's on the extra)
Kenny would be besties with Latte and would end up with her in the extra story.
Let me know if you have other questions.
Spoiler!
Yes, thanks to his Yandere personality. He's able to save Latte's life. Our MC was almost killed by a monster because of Peridot. The main bitch learned about Latte's usage of magic scroll. She manipulated it and caused our MC to teleport to a dangerous forest. Arwin would give so much love to Latte in the later part of the story. I couldn't read the novel but I got this information through namu wiki. I hope I could purchase the novel myself but it's not available in my location. TT
Do you know why Arwin kept asking about Latte's doll and what is Peridot's ending?