its basically an other-world summon novel, mostly focusing sci-fi and fantasy both.
two protagonists, a boy and a girl studying in the same school.
boy's father is in military, trains him occasionally, but boy interested in scientific nerdy stuff.he goes to girl's father who is a scientist working on government's 'secret project' to learn science, meets girl. girl wants to learn martial arts so the boy teaches her.
two start liking each other, boy comes to confess to girl on school roof. girl gets summoned in front of him before or after the confession depending on the impact you want to create.
confessing to her would give heavier responsibility vibe and a bond. while before confessing would give lighter responsibility vibe with little strings attached to each other(greater chance of seduction by another) with only some expectation on both sides. personally, i prefer the after confession choice since it gives the characters drive. also creates darker tone.
anyway, boy is depressed, goes to girls father to ask him to do something since he s a scientist. the father reveals secret to him about government research being other dimension research previously unsuccessful, but now retrieving some dimensional clues from summon site, became successful.  nothing can go through as of now, but boy might be able to go through, having some magic power rubbed off of him during summon.
but transfer is unstable, not able to pinpoint the location of the world the girl went and might jeopardize his life. the boy of course still goes(otherwise whats the point of being protag), ending in a different world, nearly losing his life to come back. he doesn't give up, trains and searches for the girl through many dimensions, becoming strong and battle-hardened the normal way(no levels or magic for him, maybe sci-fi gadgets and stuff).
girl in the meantime has levels and magic, becomes op, defeats demon king or dark lord or evil dragon or all of them within a few years. (main focus should be the boy with some occasional glimpses of the girl's swords magic advancement)
the empire or kingdom that summoned her placed curse to control her, forcing her to become the prince's fiance(they did soft and hard tactic, revealing the curse when she disagreed) gaining overwhelming popular support from the people of the world who were saved and don't know about the curse.
the boy finally arrives, learns of this. gaining level and magic (or not if you want)and powering up with unprecedented speed due to the experiences of many universes, fighting against the kingdom finally rescuing her going against popular sentiment. the girl might hesitate due to the people or not.
the boy convinces her anyway and brings her home. or if you like torturing protags and are an 'S', you can go the NTR route or make the girl suicide and boy driven to anger, destroying the kingdom or empire. I personally don't like that kind of ending though.
if you go the heavy route(after confession) don't make the boy a typical Japanese mc "don't kill" pussy, won't fit. it needs someone cynical, brooding type(though would have some ideals of sticking to one girl and taking responsibility for one's actions) who does what's necessary, killing where needed.
that being said I wouldn't mind multiple authors(if anyone at all is interested) writing from different viewpoints. exploring all the possibilities.
BTW. this is just an idea for a novel and I claim no rights to it. how I presented the whole plot is how I would write it if I did. but if anyone finds the premise interesting, they can write it however they want, change it to their heart's desire and make it their own.
the only reason I don't write it is it's not a type of story I would write. I would perhaps read it, but I don't think I create the proper vibe that can give it life if I wrote it.