Eiyuden Chronicle: Hundred Heroes

You'll have to specifically avoid getting this achievement through a standard playthrough as you'd need the materials to upgrade your base at some point.

In "Dungeons" there are harvesting points depicted by an object of sorts with vertical, yellow/orange lines animating around it. This object could be a netted trap, a pile of rocks, a small tree, the skeleton of a monster, or various other things.

Press A on them and you'll get a material of sorts (Stone, Lumber, Wheat, etc). The lines will disappear for a variable amount of time; some harvesting points respawn after a battle, others respawn after 10 minutes. All respawn when leaving/entering the dungeon.

Harvest from these 250 times and the achievement is yours. It can even be the same harvest point if you really want to waste your time in such a manner.