[MangaD]

So I've got a new phone and I don't know how to switch my content from the main to the second device..

There is no in-game feature that allows progress transfer unfortunately. Marti mentioned a while ago that this was because of security issues that would come with that feature (i.e. game getting hacked). Another solution would be to have accounts and store the progress in a server (like web version has), but that would be more expensive. Maybe Marti will find a way for this in the future.

Marti didn't respond and I wrote an email, I guess 9 days before.

If your devices are rooted, you can try Titanium Backup to backup your progress (the whole game) in your old device and then restore it with Titanium Backup in your new device. If not, then you have to resend your e-mail to Marti, because he gets a lot of e-mails and doesn't see all of them. Remember to include your old referral code and your new referral in the e-mail.