Recommended leveling methods?

The level 20 for the hidden quest should be your Fortress Level, not your Player Level... Just a heads up (^_^;) When you try to raise your Fortress Level, it'll show a 재생 mark (play button icon) on the facilities or materials you're lacking. Tapping that will switch you to the page where you can get them, so you need to fulfill all the conditions one by one. Just in case, I'll also write down how to raise your Captain Level. Repeating monster hunts (using items helps!), and the ranking rewards from the event 'Queen's Request' are probably the most basic ways to earn them. Good luck!

Captain level is just hunting from morning till night 😊