I think you mean Anime Eternal and the save key. The clearest match I found says the key drops from the Magistey enemy, which can appear randomly on maps and seems to show up more often at higher Reincarnation levels.

Where to look

  • Check map areas thoroughly, because the enemy can appear as an aura spot on the ground before it attacks.
  • Higher Reincarnation levels may increase the chance of finding it.
  • Players in that discussion also said to clear the whole map, especially later maps where key drops seem easier to find.

If you meant another game

The query text looks a bit garbled, so if you meant a different “anime gopstle” game, the exact key location may be different. The result I found most closely matches Anime Eternal rather than a game called “animle gopstle”.

TL;DR

The save key appears to come from the Magistey enemy in Anime Eternal ; keep clearing maps and watch for aura-like spawn spots.