Party Dojo
The Party Dojo (JP: パーティ道場) is a building in Deltarune. It is located in Castle Town and managed by Jigsaw Joe. It first appears in Chapter 2, once Kris transfers Card Kingdom's Darkners to Castle Town.
In the dojo, the party can attempt unique battle challenges to earn specific rewards. These also include encounter tutorials, such as grazing with the SOUL.
In Chapter 4, the dojo has been rebranded to the Love Dojo (JP: 愛の道場) and features a love theme. Thus, the party can only battle lovers.
In Chapter 5, the dojo seems to have entirely changed focus from battles to romance. However, some rejected Darkners have set up a battle frontier at the bakery.

The entrance features two fists on opposite sides of the hallway, facing away from the hallway. The dojo has a large disco ball hanging from the ceiling, and an area that resembles a boxing ring during which the challenge battles are conducted.
Jigsaw Joe stands in the middle of the dojo, where he allows the party to choose which challenge to take on. Battle's Master, formerly TP Master, wears a hat and runs a help desk located in the top left corner of the dojo. Battle's Master can inform the party about battles. Clover's bed is located in the bottom-left corner.
Several enemies appear on the right side of the dojo — initially Clover, Bloxer, and Pippins. If Werewerewire is recruited in the Cyber World, it replaces Pippins. In Chapter 4, the Pippins comments on the party finally meeting other Pippins.

During Chapter 4, the dojo is love-themed. The disco ball features heart patterns, and the square mat in the center is replaced with a heart-shaped mat. The Bloxer traces a heart shape with its arms, and the Battle's Master is renamed the Love Master. Cap'n is responsible for the dojo's new background music, Pushing Buddies. Jigsaw Joe and Love Master appear unhappy with the new branding.

Chapter 5 keeps the Dojo with it's love theme from the past chapter. The background music is changed to now be playing Pirate Dojo. The Bloxer, who was previously tracing a heart shape, has left the dojo and is implied to have gone to the Bakery, with now in it's place multiple of Bloxer's lower parts, which seem to have entered a loving relationship.
Talking to Cap'n shows him complaining on how hard it is to include Clover's leitmotif while making songs for them, being the reason for the different background music in the dojo. Cap'n says he misses his friends, and hasn't seen them for a day.
Lanino and Elnina still can be found here, talking about how the dojo is only for couples with two people, as they have a bad experience with the number three. They question if Clover counts as 1 or 3 people, then question if a couple with 4 people would be alright, as is also divisible by 2.
If Starwalker was interacted with in Chapter 1, a tiny version of him will appear between the two. They will now say the dojo is only for throuples, but they do not count one of Clover heads as she does not like Cap'n, and is implied to have a crush on Elnina. They ask Kris to keep Starwalker safe, because they don't want to be alone and change partners again.
Nubert will appear if you haven't recruited everyone, saying he won't fight you unless you do so.
- On the Party Dojo's sign, the colors of each letter in "Party" are similar to the logo of Party City.