No it's only nate, asama and horizon

It is confirmed than in an alternate future she ended in a couple with Masazumi, but it's relatively probable that it was a "chill" couple with pretty much platonic relationship.
It is also confirmed that in that alternate future, their mutual DNA was used to make a child (who takes the historical role of Masanori Fukushima ).
In the current "timeline" Futayo is only aware of her children but not of who is the other parent, but Masazumi realises it near the end. At the moment the story ends (it will be continued in the sequel though), they are still not a couple at all.

No for Naomasa, she's only with her little sister. There is a character from PA Oda that is in love with her, but that's a ... sentient tentacle. Little need to say, but despite his best effort she's not looking at him as a possible soulmate lolmao.
There is another case like that between the student council's vice president of Date (this time he's a human) who is in love with Suzu, but she's not answering his feelings as well (I mean he's a complete weirdo so that's that).


Noriki yes, but he had his soulmate from the start, his and her situation is simply complicated (she's already India's current leader at the start of the story btw), and he had to solve the situation before really starting an official relationship.

For Futayo, no, not really. In an alternate future she was married to Masazumi and had a child through their mutual dna, but that seemed mostly platonic from the vibes of it, and in the current timeline there is not yet such a thing (but it could happen in the sequel between the two too as Masazumi is aware that they had a child in the alternate timeline)

Kiyonari, yes, and a pretty strong and strong willed partner as well, full fledged couple that one.

Shirojiro and Heidi never really become that closer than they already are at the beginning, but they don't get more distant either.

There are other couples that are formed here and there but not among the main character cast that you already know of, except if I'm forgetting someone right now (well except Toori and his harem obviously).