Since I gave it enough time and there were only four comments left, I think it's time to reveal it all:

A cool traveler notebook (fits the Midori TN perfectly) from Paperchase! It has lined pages, the paper is fountain pen ink friendly and it even has its own closing elastic, so you don't need a Midori to use it.

From those four comments, only two were correct: I am using the MUJI notebook. In order to select the winner, I decided to go with the Wheel Decider, where you can set up your options on a wheel and turn it!
Reminded me of all those game shows from the '90's!

As you can see on the image below, the winner is JENNIFER! CONGRATULATIONS!!!!!

Jennifer, please get in touch with me so I can send you your notebook as soon as possible! :D

And last, a couple of pictures to show my sidekick, which is working really well, I might add.

Thank you, and happy holidays!