This is a very easy trophy to get and will likely be one of the first you ever get. From the starting point in the small village you're in, head to the house in the north-west corner and watch a small cutscene play out.
Head to the right of the village and talk to an NPC before entering the 1-time tutorial dungeon, Ouma Shrine. Upon reaching the other side, you'll unlock this achievement.
Estimated time needed: 20 minutes or less.
https://mysterydungeon.gamepedia.com/Shiren_5/Ouma_Shrine