My Nanami Standard notebook was getting beat up after a couple weeks of use and I didn't want to spend a fortune on the covers sold in the shop specifically for these notebooks. They're beautiful covers, don't get me wrong but I want to spend my money elsewhere like fountain pens or more notebooks.
I found this on Amazon and it's great. It comes in a few different colors and a small notebook is included. I'm pretty pleased with the fit and on first inspection, it seems like a durable product.
Thought I'd share an alternative to the expensive covers.
Edit: word
You could also consider a notebook cover if you're really worried. Something like this: https://www.amazon.com/Kokuyo-Systemic-Refillable-Notebook-Cover/dp/B001J5PC6W/ref=sr_1_5?ie=UTF8&qid=1523895468&sr=8-5&keywords=kokuyo+notebook+cover
You could also get a hard cover for the Seven Seas. That's what I do.
https://www.amazon.ca/dp/B001J5PC6W/ref=cm_sw_r_cp_apa_i_NBblFbFA082A5
A lot of the fountain pen friendly notebooks aren't super cute, but you could go with a leather cover and put a nice A5 book in it, like a Rhodia, Midori, or Apica.
Something cute like this:
https://www.etsy.com/listing/868351711/a5-sketchbook-notebook-journal-jotter?ref=shop_home_active_3
Or a little tougher but still classy like this:
You'll want to make sure notebook covers have either a pocket to slide the back cover of a notebook into, or stretchy bands to hold the notebook to the spine.
I have a plain leather wrap and this Kokuyo cover and I love them both.
https://www.amazon.com/dp/B001J5PC6W/ref=cm_sw_r_cp_apa_i_tAYBFbGX48EFX
You're awesome for getting her something related to her hobby <3. Also, the white pen is a TWSBI Eco and it's one of my daily pens, too. It's an excellent and reliable pen.
Its's a Maruman Mnemosyne Spiral Dot. It's super smooth and takes ink well. I use fountain pens in it.
https://www.jetpens.com/Maruman-Mnemosyne-N105-Special-Memo-Notebook-A5-Dot-Grid/pd/27112
The cover is the Kokuyo Systemic Cover. It doesn't fit 100% because of the spiral binding, though, but well enough I kept using it. The cover comes with a Kokuyo lined notebook which is also great paper.
https://www.amazon.com/dp/B001J5PC6W/ref=cm_sw_r_cp_apa_i_HbDyFbCQTCP5R
The stickers all came from the Dollar Tree, lol.
I think you may have this one? Kokuyo seems to make near little covers!