No premiere date announced yet. The new PV is here. Check out the ANN article for additional information. Synopsis of the light novel adaptation from AniList:
High school student Hojo Saito married his classmate, Sakuramori Akane, the girl who’s his worst enemy in school.
“If you tell the rest of the class we’re married, I’ll kill you”
“I don’t want them to know either. There’s no point in that.”
Their newlywed life wasn’t going so well, and they were constantly at odds. However, as they progress through their daily lives, the distance between them closes, they have more enjoyable moments together, and they gradually come to understand one another. Saito learns about Akane’s cute side, which he never saw before, and Akane gradually began to recognize the feelings that she’s been keeping inside…
The heart-throbbing newlywed life of two people who just can’t seem to be honest with each other begins here!
It is fairly young, but not unprecedented. There were a few married people in my high school while I was attending. Tonikawa is another example of a show where a high school aged character is married. Outside of fiction though, I would never suggest anybody entertain marriage until later. I dated my girlfriend (now wife) for 15 years before we married.
When I was in 7th grade there was an 8th grader showing off her wedding pictures at the lunch table. She was 14, her husband was 18, and we all lived in Alabama.
And they were siblings, so they had a lot in common, right?
Not sure, but you've got a solid 50/50 on that.