Ni No Kuni 2: Revenant Kingdom is filled with secrets to sniff out, from powerful Higgledy allies to good old-fashioned treasure chests. Most of these are tucked away in dungeons, but some chests, namely those blue ones you may have gleefully discovered and then reluctantly abandoned, are hidden in plain sight. You can't open them. Not yet, anyway.
Despite appearing early in the story, it took me 40 hours to figure out how to open these blue chests. I'm not proud of that fact, and I want to spare you the same fate, because it's actually quite easy—and worthwhile—to start cracking these puppies open. Here's what you need to do:
- Progress through the main story until you unlock Evermore. Managing Evermore is the best part of the game, so you should be doing this anyway.
- Build the spellworks. It's near the castle, just left of the armorer out front.
- Upgrade your spellworks to level three. This is going to take some saving since you have to upgrade your kingdom to upgrade most buildings past level two, including the spellworks. Don't feel like you have to sink every last Kingsguilder into it, and be sure to recruit citizens and build some basic utilities to earn Kingsguilders more quickly, but try to upgrade it to level three early on.
- Research the 'spring lock' spell found near the bottom of the research list. Luckily, there are no individual citizen requirements for this spell. You just need enough citizens who are smart enough to pull it off. You don't unlock spring lock the way you do spells like quicken growth—just complete the research like you would any other.
Voila! You can now open all the blue chests you've found in the overworld. Note that this spell won't work on the blue chests found in the Dreamer's Door dungeons. You're still going to need dreamer's orbs for those.
Oh, and if you're wondering where to find all nine Dreamer's Door dungeons, have a gander at this guide. We've also got some general tips for combat and kingdom building, plus a guide to perfectly completing the puzzle portion of the Kingmaker Trial.