As the key failed to fit in the hole.
Undertale locked door.
There is a dog behind this door.
Sea tea reward.
Nothing will open it not even the expensive mystery key item.
The protagonist can sleep in this room for 200 g yielding a similar effect to resting at snowed inn.
After that you go into sans room and will find another key on a box.
The door which bears the delta rune is surrounded by glowing mushrooms and floating particles.
If the mystery key is used on the mysterious door it reads the following text.
Anyone that s started up undertale for the first time will encounter a mysterious locked door early in the game s snowdin area.
That key will open the back door.
Frisk do not let them in.
If used during the fight against mettaton ex the following text displays.
The mysterious door is an area found in snowdin forest south of the right side of the room with the icy x s and o s puzzle.
Nothing belongs to me.
However unlike the snowed inn the money is not returned to them.
Glyde can be encountered in this room before fighting papyrus.
Handing over any of the listed items rewards a response and in most cases an item.
First you have to get the key to sans room.
In the nintendo switch version examining the door leading to mad mew mew in the dog shrine before it is unlocked yields a message saying that the door is locked by a mysterious seal as an ominous piano jingle is heard.
You used the key the lock clicks.