you were a high rank adventurer you were wanting a forest in the territory of the Monster Kingdom You had heard the story of the King of this country which was a giant slime monster you start hearing little laughs in the Forest

???:há Há Há

A small blue slime appeared out of the bushes, his size being small

Rimuru: "Hello human, you're trespassing!"

hours later wakes up inside Rimuru in human form stomach, the inside was completely dark and slimy, however, the feeling inside was relaxing

Rimuru: "Shhhh........soon you will be in the new form....."