Recommendations Smart protagonist and strong heroine in war/survival setting without harem

Hello,

I am looking for a novel, a fiction, or even a fanfiction which has the following features:

• The story must be either in French, English or Japanese. Yes, I do not mind untranslated Japanese fictions as I can read them well enough.
  • The protagonist must be a young male, between 18 and 30. He must be smart and have good knowledge of sciences.
  • He must NOT be dense or overly shy, like your standard Japanese MC. He can still be shy, at first, or emotionally slightly stupid, but not to point of not understanding other people’s emotions even when they are obvious.
  • A cold-headed and analytic MC would be preferable. The MC should not be cruel or sociopath.
  • I would prefer a protagonist who is not overly lewd, not any more than the average man (counter-example: Issei from High School DxD).
  • The MC should not have superpower. His power should come from his intellect or weapons.
• The protagonist must quickly get into a romantic relationship with the heroine. It should be done during the first half of the story.
  • The heroine must also be smart, at least about as much as the protagonist. She can also be physically strong. Mentally + physically, the heroine should be at least as strong or stronger than the protagonist.
  • The heroine must look about the same age as the protagonist.
  • The heroine must NOT be a tsundere.
  • It must NOT be a harem. There could be other girls, but the protagonist should clearly love reciprocally only the main heroine. The other girls should be just friends.
• The setting can be fantasy, modern or sci-fi, however, the two characters must be in a survival situation, possibly inside a war. They must face hardships and struggle to survive. Their love should blossom inside that bloody battlefield. There should be suspense and an apparent lack of plot armor, or plot-induced-stupidity.
• The story may be 13+, 15+ or 18+.

Example of the ideal story I am looking for:

[MC], an university student majoring in engineering, found himself transported into a fantasy world where the very survival humanity is threatened by demons and other magical beasts. Inside this hopeless situation, he met a beautiful and an exceptionally skilled maiden, the only survivor in her platoon. Together, they must cross 20 km of no-man-land to join the remaining allied force, and then desperately fight back against the enemy together with what is left of the human army. The 21-century knowledge of the MC, combined with his gifted tactical intellect, supported by his partner, will prove to be the turning point of this savage war.

Note: I already know Release that Witch. Something similar would be ok, but with on a smaller scale and with a much bigger focus on romance.

 

What a hard requirement. Smart MC is already rare enough, and smart MC with that setting is almost non existent. I would like to be proven wrong though if somebody can give a suggestion.

Edit: If the setting doesn't have: no harem, smart heroine, no cruel mc tag then maybe I can give some suggestion.

 

Altina the Sword Princess .

 

Side Character Transmigrations: the final boss is no joke

 

Altina the Sword Princess, Invisible Dragon, Genjitsushugi Yuusha no Oukoku Saikenki, and that other one where a gladiator substitutes for a dead prince

 

So by smart MC do you mean that character is smart, or that everyone else needs special education. Because one of these choices can open you up to many titles.

 

Rakuin no Monshou; Orba life has treated him badly, is a slave gladiator who is given the opportunity to replace a dead prince, is a strategist and with the sword and does not let himself be controlled. Vilena is his fiancée and princess of an enemy country, he has personal and thinks well what he does. The story is full of political plots but it is very interesting and it is also complete I finished it in a month.

 

Vermillion, plainly good novel

 

Story: The Scientific Approach To Getting A Harem
https://www.fanfiction.net/s/12699487/1/The-Scientific-Approach-To-Getting-A-Harem

In this series Issei is genius(Tony Stark level) that even hating typical Harem protagonist. His love interested is Irina and i think the title is misleading cuz theres no harem in this series (yet maybe). It's not that long so just give it a try.