Quest 30 - Depository of Love and Trust (愛と信頼の預かり所)
Location - Any storage facility
Requirement - Lv 10
Initial Reward - Storage is unlocked / Old Document
Replay Reward - Single phial
EXP/Fame - 1760P / 17P
Talk to an NPC at any storage facility (marked by the blue vault icon) when level 10 or above to accept this quest.
They will ask you to defeat a Bubble Slime (バブルスライム) to get the item Glittering Ink (きらめきインク).
A Bubble Slime
Bubble Slimes can be found in: Glen Region East (グレン領東) [F2], Azlan Region (アズラン地方) [E3], Mogarim Highway (モガリム街道) [C4], Orphea Region East (オルフェア地方東) [F4], and Lenam Fields (レーナム緑野) [F4]. Each of these locations is near one of the five starting areas, meaning that regardless of location you should have no trouble finding a Bubble Slime.
Hint: When you enter battle with an enemy type you need to defeat for a quest, a blue circle will briefly flash in front of that enemy. You may have to kill a few Bubble Slimes to successfully get the item drop, but once you get it a textbox will appear after the battle and future encounters will not have the blue circle.
Once you have gotten the item drop, return to any storage facility and you will successfully gain access to the item storage vault!