I love this ship so goddamn much so take headcanons
Setsuka and Mikado will steal Nikei's hat and then play keep-away with it while Nikei just tries to get it back
They once attempted to play FNAF, which ended in Nikei hiding in Mikado's cape and jumping whenever a jumpscare happened, and Setsuka just playing through the game effortlessly. Mikado was just sitting there cuddling Nikei and staring at the screen, enthralled while also wondering if the animatronics were magic
They like making lemonade together whenever it's hot out, especially when they just got a fresh batch of lemons. Eventually they started growing them themselves
. Setsuka will surprise her boyfriends with hugs from behind. Mikado usually melts into it while Nikei jumps, mutters tsundere things and then melts into it.
Back when Nikei didn't have his male body, whenever he felt dysphoria he'd hide under the blankets muttering about his body until Setsuka and Mikado find him. He'll try to badmouth himself and Setsuka and Mikado will not have that and will smother him with love and affection.
Setsuka basically forces Mikado and Nikei to watch Disney movies. Mikado really liked Ratatouille while Nikei's favorite is Zootopia. Setsuka's favorite is Big Hero 6.
Nikei likes making little comics of original characters whenever he's not working (which is a rarity) and Setsuka and Mikado will steal and fangirl over them and compliment them therefore flustering Nikei.
Mikado once found a snake outside and brought it in as a pet, but Nikei is terrified of snakes so Setsuka had to talk Mikado out of it while Nikei hid behind her
Nikei once accidently got himself in a bad situation and the person was about to hurt him but Setsuka and Mikado showed up in the nick of time, so now that person is dead and they had this big cuddling session with Nikei afterwards
Mikado loves apple pie so sometimes Setsuka and Nikei will make him one as a treat.
Nikei is not allowed to grocery shop by himself because he can and will get only candy, pastries, and ice cream.
For Setsuka’s birthday, her boyfriends took her to a petting zoo. They all had a really good time there. Setsuka especially loved the little ducks.
A moose once wandered into their backyard. Nikei wrote numerous headlines about it, Setsuka wanted to see if she could ride the moose, and Mikado kinda just stared.
Setsuka and Mikado will tease Nikei about his height constantly. They will stop if he starts getting insecure about it, though.
Mikado enjoys building things with legos so for his birthday Nikei and Setsuka got him a huge lego set. Mikado’s reaction was :D for the rest of the day. And he somehow managed to build the entire thing in an hour.
They are impulsive as heck.
Nikei likes decorating the house, so Setsuka and Mikado will walk into rooms and see random lace and streamers and the occasional painting on the wall.
Since Nikei and Mikado don’t really have a childhood, Setsuka makes them do childhood activities, like playing with play-doh.
When Nikei believes he’s alone, he’ll put music on his phone and dance around the house and sing along, and Setsuka and Mikado will both film and watch him with loving smiles on their faces.