Kagura's plan worked.
she sanded the coin to fairy tail, asked Erza how to sand a letter to Jellal, started researching on reequip magic until she know how it worked, putted the fake apology letter in place and when she felled the effect of the coin's soul magic, she drugged herself so her body will not wake up until the next morning. in this time, she was Erza for 1 day or so.
she remembered what she did...
first, when she woke up in fairy tail, she started playing a role, like she were on a stage. the name of the actress was Kagura, but the role was Erza scarlet's role, and when she was on stage, she was Erza.
she left the guild for the day, heading toward Erza's home. when she arrived, she started using Erza's magic, checking what armors and clothes were now hers. she wasn't disappointed, Erza's collection had a lot of useful armors and stylish cloths, even a Battle kimono like hers, which Kagura changed into. "I can get used to this body", she says while starting to write a letter to Jellal. when she finished writing the latter, she changes out of her kimono and got to the delivery company, using Erza's secret delivery service to send Jellal a letter from erza, saying she has something very important to tell him, face to face. she has written the letter in a way that will make Jellal think it is important, and to make him rush to magnolia.
"great! with my letter done, I need to go on a mission for my new guild, to avoid Erza when she will come here"
'Erza' then go home, ready herself, and then goes to the hot springs to relax and appreciate her new body. "just few more days until I meet him" she mutters to herself.
* the day after *
Kagura woke up fast, and started working. for an hour or so, she tried to make her imitation of Erza even better. she wanted to look, sound, and be like the real Erza.
after that, 'Erza' goes shopping for new clothes, more suiting her style, then re-check her armor collection until she controls them like the real Erza 'the lest month was worth it, I am strong just as Erza is, if not stronger.' she then switches her armor to check to more suits, Erza's rubber armor and the defense breaker armor. she then looked at the mirror, admiring her new form. "this one will be useful, I am an expert in The katana and with unarmored fighting" she smile at 'her' reflection, checking her new body's movement and trying to summon Erza's arsenal of katanas.
after a quick change, 'Erza' goes to the forest near Magnolia, to try fighting with her 'new' magic. after her magic training, Kagura then goes to her new guild, ask Mira for a strawberry cake 'Erza always eats those', go to the guildmaster, take a mission that will last two to three days and seats to eat her cake. Kagura ate strawberry cakes before, but with Erza's taste, it was amazing. she then remembered how Erza behaved when someone dropped her strawberry cake, and if someone will dropped her she will behaved the same way, not just because she needed to look like Erza, but she will also hate the miserable soul who will spill her new delicious strawberry cake.
'do I really need to leave this body? I feel so natural in here, like in my own body, but I'm stronger here, and more beautiful...' wonders Kagura while living fairy tail and going to the mission she took. she looked at Erza's shoulder and saw the fairy tail mark, 'I guess I'm no longer a Mermaid Heel mage, but a fairy tail one... I'll have to destroy the coin, because now I am Erza Scarlet, not just as a role on a stage. I want to keep this amazing body, I didn't know I will like it so much, but, I sure glad I did make the plan's second stage a body swap with Erza, my plan to kill Jellal.'