I'm not sure specifically what the'sama sama letter day story' is about as it's not a widely known common story. It could be a very personal or a story from a specific local or cultural context.
Here are some recommendations for novels similar to the marines:
1. "Refusing Qinghua's postgraduate studies, my liver became an officer." Author: Yuze Guardian
2. I'm Really Here to Maintain Peace. Author: Ghosts Never Get Lost
3. Film and Television Begins with the SEALs, by Little Soldier
4. " The life of an admiral from scratch."
5. " I'm a commander in the army."
6. "I'm a special forces soldier in the soldier assault."
These novels covered different types of Marine stories, including military, military life, and military science fiction. I hope these recommendations will meet your needs.
In marines romance novels, the setting of military life provides a backdrop full of challenges. For example, long - distance relationships due to deployments are common themes. The love stories are often about how the characters overcome these difficulties. Also, the physical and mental strength of the marines is an important aspect that is often intertwined with the romantic plot.
The Kaguya-sama manga is indeed finished. It ended after a successful run, leaving fans with memories of an engaging and enjoyable story. The final chapters tied up loose ends and delivered a conclusive ending.