Are you on the second dungeon? If you're struggling, there are additional abilities you can unlock by clearing the Mansion levels and the Arena minigame.
Apologies for any lack of clarity. I have some plans to add a bit more guidance into the game.
Ah, in that case you just need to get past floor 10. If you're struggling at any point, purchasing the green tea donut from the shop will turn down the enemy strength in the dungeon.