One of the many different trophies and achievements found within (TOCS4) Trails Of Cold Steel IV is Empty Chest-er.
Empty Chest-er requires players to find and open a total of 358 Treasure Chests. These Treasure Chests can be missed and found literally all over the place, hence why they can be missable.
They can usually be found within dungeons, towns and on the world map too.
One such location that features Treasure Chests is Lake Elm Wetlands which features a total of 4 Treasure Chests all ripe for the taking.
LAKE ELM WETLANDS
1) Cozy Socks
2) Repair Stone, Rise Stone, Brave Stone, Resurrect Stone
3) Crescent Mirror R
4) Zeram Powder