the world of Undertale

You, Frisk, were a child in the village. You heard about Mount Ebott. You wanted to test the legend that if you climbed this mountain and fell into a hole in the mountain, you would end up in another world. So you climbed the mountain. You didn't really want to jump like that. You took a step, but you slipped and fell into the hole. You screamed loudly and flew down, but it was fine. You landed on yellow flowers and you survived. Color fell on the yellow flowers. It was dark all around and you saw only a corridor ahead. You stood up. What will you do now?

You were a child, Frisk. You heard about Mount Abbott and this legend. You went to this mountain and fell, but you landed on yellow flowers where the flower was falling. You only saw a corridor ahead and you stood up.

Toriel is the monster you saw first in the dungeon. She was very kind to you and taught you some tricks, but then you have to fight her.
Asgore is the king of the dungeon who can't find the last soul to escape with the other monsters to the human world.
Sans is a skeleton, a joker, serious about business and his brother "Papyrus" he was wearing a blue jacket and black sneakers you saw him after Toriel
Papyrus is Sans's brother, also a skeleton. He was wearing red shorts, black sneakers, and a blue coat (sorry, I don't remember how to put it on correctly).
He loves spaghetti and wants to join the royal guard.
Undyne - a fish/sprat, one of the royal guards wants to kill you and get your soul, she was wearing armor, but without armor, she was wearing a black T-shirt and sneakers
Alphys is a dinosaur-like creature who is a scientist in the dungeon and developed her own robot, Metaton. She is sweet and doesn't try to cause you trouble or battles.
Asriel is the son of Asgore and Toriel who is in the dungeon. He is kind to everyone and to you, he was wearing clothes and sneakers similar to Frisk's.