Your first destination in the land of Kitakami is Mossui Town, where you meet Carmine and Kieran.
Battle Carmine
Before Carmine will let you into Mossui Town, you have to face her in battle. However, it's OK if she defeats you; the story will continue either way. The levels of her pokémon, and the prize money, will depend on whether you have finished the main story or not. She has a level 12/60 Poochyena, a level 12/60 Vulpix, and a level 13/60 Poltchageist. If you win, you get 728/3360 Pokédollars for winning.
Go to the Community Center
After the battle, there will be a cutscene, and the town Caretaker asks you to go to the Community Center. When you approach it, there will be another cutscene.
You can optionally talk to the person behind the desk to change your settings for the appearance of the menu depending on your location.
When you're ready to proceed, go up to the double doors that lead to the bedrooms, and say Yes. There will be a cutscene. You will get the Roto-Stick, which adds new features to your camera. You also learn the Eureka emote. The emote is in the list of Selfie Mode emotes when using the camera.
Afterward, talk to Carmine and Kieran, and there will be another cutscene. When Carmine asks if you want to pair up with one of them, say Yes. Then when she asks if you will battle Kieran, say Yes. (If you refuse, you won't be able to progress until you talk to Carmine again and agree to battle Kieran.)
Battle Kieran
It's OK if Kieran defeats you; the story will continue either way. Kieran has a level 12/59 Sentret and a level 12/60 Yanma. If you win, you get 528/2640 Pokédollars.
Explore Mossui Town
Afterward, the Caretaker will mark the locations of the three signs on your map. You can buy supplies at Peachy's in Mossui Town any time. Kieran says to visit the signboard to the west first, but before you go, you can explore the town.
Get a Call from Director Clavell
If you purchased the DLC, you will now get a call from Director Clavell. (If you have the DLC but you don't get a call from Director Clavell, save and close the game, then check your account in the eShop to make sure you downloaded the DLC, then continue your saved game.) You can optionally go to the Director's Office in the Academy in Paldea now to start part 2 of the DLC: The Indigo Disk. Keep in mind that the pokémon you will face in part 2 of the DLC will be around level 70, even if you haven't finished the main story. It will help if you have all 8 Gym Badges from the Paldea Pokémon League before you start The Indigo Disk, but it is not a requirement.
Find Items in Mossui Town
In Mossui Town, you can find some items, such as TM128 Amnesia in the truck behind Peachy's, TM173 Charge on the roof of the Community Center, and TM036 Rock Tomb on a hill northwest of the Community Center. Beneath the eastern bridge of the town, you can find TM177 Spite.
After you have healed your pokémon several times, the Pokémon Center lady will give you the Upside-Down Double Peace pose. Press up on the directional pad to find it in the Emotes list. She will eventually teach you the Poké Ball emote, which you can find when you use your camera in Selfie Mode. The Poké Ball that you hold up will be the one that your lead pokémon is in.
Meet Perrin
When you go west, you will see a photographer taking pictures. This is Perrin, who will take your photo, and will say to come back after you have registered 150 pokémon in the Kitakami Pokédex.
Go West
When you are ready, go west and you will arrive in the Apple Hills.